TITANIUM SURFACE TREATMENTS FOR ADHESIVE BONDING

REPtr NO. NADC-82032-60

TITANIUM SURFACE TREATMENTSFOR ADHESIVE BONDING

S. R. Brown and G. J. PillaAircraft and Crew Systems Technology Directorate

NAVAL AIR DEVELOPMENT CENTERWarminster, Pennsylvania 18974

31 MARCH 1982

PHASE REPORTAIRTASK NO. WF61-542-001

Work Unit No. ZM520

APPROVED FOR PUBLIC RELEASE DISTRIBUTION UNLIMITED

DTIC

ELECTE

C..) Prepared for SNAVAL AIR SYSTEMS COMMAND

Department of the Navy AWashington, DC 20361LA-

1=98205 21 029

REPORT NUMBERING SYSTEM - The numberiq of tedinical project reports issuad by the Naval Air DevlopmentCenter is arranged for specific identification purposes Each number consists of the Center acronym, the caledar'year in vwch the number was assigned the seqence number of the report Withn t specific calendar yaw, andthe official 2-digit correspondence code of tOn Command Office or the Funrctionel Directorate responsibe ft orreport. For example. Report No. NADD78015-20 indicates the fifteeth Center report for the year 1978. and pearedby the Systems. Directorate. The numerical codes are as follows:

CODE OFFICE DR DIRECTORATE

00 Commander, Naval Air Developmeiit Center01 Technical Director, Naval Air Development Center02 Comptroler10 Directorate Command Projects20 Systems Di rtorate30 Senr= &t Avmmc Technology Directorate40 Communication ht Navigation Technology Directoat50 Software Comput Directoate60 Aircraft Er Crew Systems Technology Directorate70 Planning Assessment Raesore80 au &uo

PRODUCT ENDORSEMENT - The discuion or iistmucthns concerning commercial products herein do not constituteiLn croreen the overment nor dotheyconveyoriy the lcensorrht touse such product.

APPROVED BY: n

3DATE

J/ .WODCK.US

UNCLASSIFIEDrECUAITY CLASSIFICATION OF THIS PAGE (W)m Date Ent.r.*

REfAD MMTUCTM8NREPORT DOCUMENTATION PAGE MPLETnoRMStro COMPLETINGA IroRamsI. REPORT NUMBER 2. GOVT ACCESSION NO. S. RCCIPIENT'S CATALOG NUMBR

4. TITLE (end Subllle) F. TYPE Of REPORT & PCOO COvlrtCO

TITANIUM SURFACE TREATMENTS FOR ADHESIVEBONDINGPhs SS. PERFOMINGONG REaPORT NUMBER

7. AUTHORe) S. CONTRACT OR GRANT NUMUsRe.)

S. R. Brown and G. J. Pilla

Aircraft and Crew Systems Technology Directorate Work Unit No. ZK520AorEAk WORK NIT NM20S

Warminster, Pennsylvania 18974

I. CONTROLLING OFFICE NAME AND ADDRESS It. REPORT DATE

Naval Air Systems Command 31 March 1982Department of the Navy 13 NUMBER OF PAGES

Washington, D. C. 20361 5114. MONITORING AGENCY NAME & AOORESS(II different from Controlling Offlic) IS. SECURITY CLASS. (of t is repor)

UNCLASSIFIED

ISo. OECLASSIPICATION/DOWN GRADINGSCHEDULE

16. DISTRIBUTION STATEMENT (of this Report)

Approved for Public Release; Distribution Unlimited.

17. DISTRIBUTION STATEMENT (of the abstract entered in Block 20. If different fom Report)

II. SUPPLEMENTARY NOTES

19. KEY WORDS (Contlnue on et%'r '.smy and Identify by block numbet)

Titanium Pretreatm=ntsWedge TestAdhesive BondingDurability Testing

20. ABSTRACT (Conti .e i reveres id* If noesawy and identify by 536. Sumew)

> The aircraft industry prepares titaniumsurfaces for adhesive bonding using

various types of abrasive, etchant, chemical and anodize treatments. A study

was made to determine pretreatment effects on adhesive bond durability of tita-

nium under severe environmental conditions of temperature, humidityand stress.

Replicate sets of Ti-6AI-4V titanium specimens were provided to aircraft manu-

facturers who prepared the sets using eleven different ptetreatment processes.

The manufacturers also bonded the specimens with the same four adhesive

systems. Wedge specimens, bonded from 0.150-inch thick Ti-6A1-4V titanium were

DD I FoMM7 1473 EOITION OF I NOV 05 iS OiSOLEATS/d 0102-LF-014.6601 UNCLASSIFIED

SECURITY CLASSIFICATION OF THIS PAGE ( m.. Date 5nweiQ

UNCLASSIFIEDSILCURITY CL"IATIncrof, TH7bIS PAGU (WI.., Data aer.4

-7tested in a 140 F, 100% relative humidity atmosphere for a period of eightweeks. Chromic acid anodize, alkaline etch, chromate-fluoride and alkalineperoxide treatments resulted in substantially lower crack growth rates thanphosphate-fluoride treatments. There was a alight difference in performanceranking of bonding pretreatments depending upon the adhesive system used.,

Acceondf Toi"TSGRA&I

Avsil~bilitY C0460

M~ail gui/o'

TDtst I special

SICPT CLASIICAIO OfTHI~w S PAeGILMOM 60 RRVa d

NADC-82032-60

SUMMARY

INTRODUCTION

Effective surface pretreatments are necessary to prevent premature failureof adhesive bonded titanium in naval aircraft and missiles. Abrasive, etchant,chemical and anodize methods are used by the aircraft industry to preparetitanium surfaces for adhesive bonding, but the durability has not beenestablished for the different pretreatment processes. A crack extension wedgetest study was made to determine pretreatment effects on the durability ofadhesively bonded titanium.

RESULTS

Eleven titanium pretreatment processes were evaluated for adhesive bonddurability using the wedge test method. Four film adhesives with primers,FM300K/B2127, FM73M/BR127, M329/M329 Type II and EA9628H/BR127, were used tobond the wedge test specimens made from 0.150-inch Ti-6A1-4V titanium sheet.Specimens were exposed in a 140 F, 100% relative humidity (condensing) environ-ment and crack growth measurements were taken at intervals during the 56 dayexposure period. The average crack opening measurement (a+Aa) for each pretreat-ment after 56 days was as follown:

Average Crack OpeningID Pretreatment (a+Aa), inches

CA5-4 5 volt chromic acid anodize with fluoride 2.44TU-8 Turco 5578 2.47CA1O-4 10 volt chromic acid anodize with fluoride 2.48LP-6 Pasa Jell 107C - liquid hone 2.50AP-9 Alkaline peroxide 2.55DA-5 Dapcotreat 4023/4000 2.71DP-2 Pasa Jell 107N - dry hone 2.77PF-3 Phosphate fluoride with HNO3 predip 3.98PF-4 Phosphate fluoride 4.47VA-7 VAST 4.72PF-l Phosphate fluoride - PA modified 4.89

Crack growth during exposure testing (Aa) was predominately of the adhesivefailure mode at the interface between the titanium and the adhesive/primer layer.

CONCLUSIONS

The most durable titanium pretreatment systems as determined by wedge crackextension testing were chromic acid anodize with fluoride (both 5 and 10 volt),Turco 5578 alkaline etch, liquid hone Pasa Jell 107C and alkaline peroxide.

Dapcotreat 4000 and dry hone Pasa Jell 107M were slightly lower in overallperformance than the above five pretreatments.

The three phosphate fluoride pretreatments along with the VAST pretreatment

* J ...I... ... ... . .... .

NADC-82032-60

resulted in significantly longer crack grovth lengths and poorer durabilitythan the other pretreatments.

When using wedge tests, total wedge crack openings (a+Aa) are preferred over

crack growth lengths (Aa) as a measure of durability.

RECOMMENDATIONS

Pretreatment methods recommended for adhesive bonding of titanium arechromic acid anodize with fluoride, Turco 5578, Pasa Jell 107, alkaline peroxideor Dapcotreat 4000. Production experience is limited with the chromic acidanodize and alkaline peroxide processes. Alkaline peroxide solutions areunstable so stringent production controls must be used with this method.

Phosphate fluoride and VAST pretreatments should not be used where highdurability titanium adhesive bonds are required.

FUTURE PLANS

The alkaline peroxide process will be developed to improve both stabilityand determine effective operating ranges. Advantages of the alkaline peroxidemethod include: the bath does not contain either chromate or fluoride ions,anodizing equipment is not required, operating conditions are reasonable forproduction, and the treatment provides a stable, bondable surface.

ii

NADC-82032-60

T A BLE O F CO0N TE NT S

Page

SUMMARY............................. .. .. .. .. ....

Introduction............................ . .. ..... . . ... .. .. .....

Results......................... .. . . ... . . .. .. ......

Conclusions ....... ........................ . . .... . .. .. .. .....

Recommendations.. ........................ .. . . .. .. .. .. .. ....

Future Plans.............................. .. ...... o . .. .. .. . ...

LIST OF TABLES....................................iv

LIST OF FIGURES....................................v

BACKGROUND................. ......................

TITANIUM PREBOND PROCESSES AND ADHESIVE SYSTEMS................2

WEDGE TEST EXPERIMENTAL PROCEDURES........................3

RESULTS AND DISCUSSION.................................5

Crack Growth Rates.................................5

Total Crack Openings.................................9

Wedge Test Fracture Mechanics..................... ...... 24

Fracture Surfaces................................27

CONCLUSIONS.....................................38

RECOMMENDATIONS.....................................38

FUTURE PLANS........................................38

REFERENCES.......................................39

---- . ..... • . .. ,

NADC-82032-60

LIST OF TABLES

Table No. Title Page No.

I Crack Opening Measurements ....... ............... 10

II Combined Averages with All Four Adhesives ... ........ 12

III Wedge Test Crack Growth Data of PF-I Phosphate FluoridePA Modified Pretreatment .... ................ ... 13

IV Wedge Test Crack Growth Data of DP-2 Dry Hone Pasa Jell107C Pretreatment ...... .................... ... 14

V Wedge Test Crack Growth Data of PF-3 Phosphate Fluoride/HNO (Nitric Acid) Predip Pretreatment ........... ... 15

3

VI Wedge Test Crack Growth Data of PF-4 Phosphate FluoridePretreatment ....... ...................... ... 16

VII Wedge Test Crack Growth Data of CA5-4 Chromic AcidAnodize/Fluoride 5 Volt Pretreatment ............ ... 17

VIII Wedge Test Crack Growth Data of CA1O-4 Chromic AcidAnodize/Fluoride 10 Volt Pretreatment . .......... 16

IX Wedge Test Crack Growth Data of DA-5 Dapcotreat4023/4000 Pretreatment .... ................ ... 19

X Wedge Test Crack Growth Data of LP-6 Pasa Jell 107CWet Hone Pretreatment ..... .................. ... 20

XI Wedge Test Crack Growth Data of VA-7 Vast Pretreatment . 21

XII Wedge Test Crack Growth Data of TU-8 Turco 5578Pretreatment ....... ...................... ... 22

XIII Wedge Test Crack Growth Data of AP-9 Alkaline PeroxidePretreatment ....... ...................... ... 23

iv

NADC-82032-60

LIST OF FIGURES

Figure No. Title Page No.

1 Participating Organizations in the Titanium BondingPretreatment Program ................... 1

2 Bonding and Cutting Steps in the Preparation ofTitanium Wedge Specimens ........ ................ 2

3 Wet Grinding and Dry Sanding Steps in the Preparationof Titanium Wedge Specimens ........ ............... 4

4 Crack Growth Rates for Titanium Bonding Pretreatments. . 6




8 Wedge Test Results of BR127/FM300K after 24 HoursExposure to 140 F, 100% of R.H ....... ............. 9

9 Wedge Test Results of Metlbond 329 Type 11/329 after24 Hours Exposure to 140 F, 100% R.H. .. .......... 9

10 Strain Energy Release Rates ... ............... .... 25

11 Strain Energy Release Rates ... ............... .... 26

12 Titanium Wedge Specimens with As Machined Edges ... ..... 27

13 Wedge Specimens of BR127/FM73 after 24 Hours Exposureto 140 F, 100% R.H ..... ................... ... 28

14 Wedge Specimens of Metlbond 329 Type 11/329 after24 Hours Exposure to 140 F, 100% R.H ............ ... 29

15 Montage of Crack Extension in Wedge Specimen ...... 29

16 Opened Wedge Specimens with PF-l Phosphate Fluoride PAModified Pretreatment and BRI27/FM300K Adhesive System . 30

17 Opened Wedge Specimens with DP-2 Dry Hone Pasa Jell107C Pretreatment and BR127/FM300K Adhesive System . . . 31

18 Opened Wedge Specimens with PF-3 Phosphate Fluoride/HNO (Nitric Acid) Predip Pretreatment and BRl27/FM300KAdhasive System ............ ................ 31

v

NADC-82032-60

L I S T O F F I G U R E S (C O N T'D)

Figure No. Title Page No.

19 Opened Wedge Specimens with PF-4 Phosphate FluoridePretreatment and BR127/FM300K Adhesive System ......... 32

20 Opened Wedge Specimens with CA5-4 Chromic Acid Anodize/Fluoride 5 Volt Pretreatment and BR127/FM300KAdhesive System. ...... .................... .... 32

21 Opened Wedge Specimens with CAIO-4 Chromic Acid Anodize/Fluoride 10 Volt Pretreatment and BR127/FM300KAdhesive System ........... .................... 33

22 Opened Wedge Specimens with DA-5 Dapcotreat 4023/4000Pretreatment and BR127/FM300K Adhesive System ... ...... 33

23 Opened Wedge Specimens with LP-6 Pasa Jell 107C - WetHone Pretreatment and BR127/FM30OK Adhesive System . . . 34

24 Opened Wedge Specimens with VA-7 Vast Pretreatment andBR127/FM300K Adhesive System .................... 34

25 Opened Wedge Specimens with TU-8 Turco 5578 Pretreatmentand BR127/FM300K Adhesive System .. ............ . 35

26 Opened Wedge Specimen with AP-9 Alkaline PeroxidePretreatment and BR127/FY300K Adhesive System ... ...... 35

27 Opened Wedge Specimens after 56 Days ExposureBR127/FM73M ....... ....................... .... 36

28A Opened Wedge Specimens after 56 Days ExposureM329 Type II/M329 ...... .................... ... 36

28B Opened Wedge Specimens after 56 Days ExposureM329 Type II/M329 ..... .................... ... 36

29 Opened Wedge Specimens after 56 Days ExposureBR127/EA9628H ...... ...................... ... 37

vi

NADC-82032-60

BACKGROUND

Adhesive bonding is widely used to iLrove design and reduce costs whenjoining titanium components in advanced aircraft and missiles. The bondingprocess is especially applicable to joining fiberglass/epoxy or graphite/epoxy composite materials with titanium since it eliminates or minimizesmechanical fasteners. Adhesive bonded titanium joints, however, are quitesusceptible to severe environmental conditions encountered by naval aircraft.Most bond failures originate at the titanium surface illustrating the need foreffective pretreatment prior to adhesive bonding. A number of pretreatmentshave been developed for titanium, but the airframe adhesive bonding industryhas not determined which pretreatment processes give the most durable adhesivebonds.

The Naval Air Systems Command (NAVAIR) (AIR-5304) undertook a program ofengineering and scientific studies to select the most effective pretreatmentprocess for adhesive bonding of titanium. The Naval Air Development Center(NAVAIRDEVCEN) (Code 6062) managed the program and conducted the crack extensionwedge test studies under AIRTASK No. WF61-542-001, Work Unit No. ZM520 (refer-ence (a)). U.S. Army Armament Research and Development Command (ARRADCOM),Dover, New Jersey, provided all titanium specimens and conducted the sustainedload stress durability program under reference (b). Martin MariettaLaboratories, Baltimor:e, Maryland, studied effects on bond durability oftitanium pretreatment characteristics and surface reactions under reference (c).Nine airframe manufacturers and three adhesive suppliers also contributed tothis program. Program participants, along with their principle functions, areshown in Figure 1.

NAVAL MRE STSU= CON

BONDINGIAT PRTRATEN PROGRA

SBEN"I e HO0tM U4AOUU ICIA

moms"U• IgNIS IPMN

FIGURE 1. PARTICIPATING ORGANIZATIONS IN THE TITANIUMBONDING PRETREATMENT PROGRAM

NADC-82032-60

A program that incorporates adhesive bond durability tests with surfacecharacterization studies of titanium pretreatment processes is expected toresolve a number of problems and advance adhesive bonding technology.

TITANIUM P RE BOND PROCESSES

AND ADHESIVE SYSTEMS

The aircraft and space industry was surveyed to determine current pro-duction methods for pretreating titanium for adhesive bonding. Manufacturersrepresenting the different pretreatment processes were invited tn participatein the comprehensive program by pretreating and bonding specimen sets. Somerecently developed processes were included in the eleven pretreatments andmodifications studied in this program as follows:

ID Temperature/Times

PF-1 Phosphate fluoride treatment after a R.T., 2 minutesHF/HNO3 /NaSO4 pickle

DP-2 Pasa-Jell 107M treatment after dry hone R.T., 10-15 minutesabrasion

PF-3 Phosphate fluoride treatment after: R.T., 2 minutes(2) HNO Npredip(2) HF/AtNO3/NaSO4 pickle

PF-4 Phosphate fluoride treatment after R.T., 2 minutesHF/HNO3 pickle

CA5-4 Chromic acid solution plus HF R.T., 20 minutesAnodize at 5 volts

CA10-4 Chromic acid solution plus HF R.T., 20 minutesAnodize at 10 volts

LP-6 Pasa-Jell 107 C7 treatment after: R.T., 15-20 minutes(1) liquid hone(2) alkaline clean

DA-5 Dapco treat 4023/4000 R.T., 15 minutes

VA-7 VAST treatment R.T., 15 seconds(maximum 15 minutesin solution)

TU-8 Turco 5578 190 F, 10 minutes

AP-9 Alkaline Peroxide treatment 130 F, 25 minutes

2

-I

NADC-82032-60

Complete bath preparation and process conditions contain proprietary informa-tion so only p-atreatment types, solution temperatures and treatment timesare included in this report.

The adhesive systems selected for pretreatment adhesive bond durability

studies included two 250 F cure and two 350 F cure film materials as follows:

ID Adhesive System Cure Conditions

Wl FM300K/IBR127 350 F, 40-50 p.s.i., 1 hour

W2 FM73M/BRI27 250 F, 40 p.s.i., 1 hour

W3 M329/M329 Type II 350 F, 40-50 p.s.i., I hour

W4 EA9628H/BR127 250 F, 40 p.s.i., 1 hour

Adhesively bonded wedge specimen sets are identified by the prefix "W" followedby the number of the adhesive system. The same pretreatment and adhesive codesystems are used in reports on the related studies by ARRADCOM and MartinMarietta.

WEDGE TEST EXPERIMENTAL PROCEDURE

All wedge specimen assemblies were prepared from 6 by 6 by 0.150-inch thicksheets of Ti-6AI-4V titanium supplied by ARRADCOM. Bonded assemblies werereturned to NAVAIRDEVCEN for preparation and testing. The returned assemblieswere cut into 1-inch wide specimens as shown in Figure 2.

TWO 0.150 IN. THICK SHEETS OF TI-SAL-4V

WERE SURFACE TREATED, PRIMID AND

SONDED FOR WEDGE TEST SPECIMENS.

1 2 4 6

EACH SONDED SECTION WAS CUT INTO

FIVE I IN. z e IN. SPECIMENS WITH A IN.

MILLING CUTTER.

SI

1 SN.

FIGURE 2. BONDING AND CUTTING STEPS IN THE PREPARATIONOF TITANIUM WEDGE SPECIMENS

3

NADC-82032-60

Conventional machining methods covered the adhesive bondlines with metal shavingsmaking it difficult to determine crack tip locations during wedge testing. A wetgrinding procedure was developed to remove metal from either side of the bond-line leaving an 0.010-inch protrusion of the adhesive layer sandwiched betweenthin metal layers as shown in Figure 3. Dry belt sanding removed the protrusionsand provided unobstructed bondlines for accurate crack tip readings.

ADHESIVE ,ONDLINE .O ,n.

WET GROUNDD E.P_

WET GRINDING WAS UID TO REMOVE METAL

FROM THE EDGES LEAVING 0.010 PROTRUSIONS

OF THE BONDLINE ON BOTH SIDES OF EACH

SPECIMEN.

PROTRUSIONS WERE REMOVED BY DRY BELT SANDING I IN.

W(TH AN 80 GRADE BELT AND FINISHED WITH

A 120 GRADE BELT. 0 IN.

FIGURE 3. WET GRINDING AND DRY SANDING STEPS IN THEPREPARATION OF TITANIUM WEDGE SPECIMENS

Standard dimension 0.125-inch thick wedge specimens as described in ASTMMethod D 3762 were used in this study. Wedges were fabricated from 303 stainlesssteel. One hour after inserting the wedges, initial crack lengths (a) weredetermined and marked on both sides of each specimen. Specimens were thenexposed to the 140 F, 100% relative humidity (condensing) test conditions.Crack growth readings (Aa) were made after exposure times of 1, 4, 24, 48 and96 hours, and 1, 2, 4 and 8 weeks, Crack tip locations were determined with astereo binocular magnifier at 30X magnification. At completion of the 8-weekcrack growth test period specimens were split apart for failure mode analysis ofbondline surfaces.

4

NADC-82032-60

RESULTS AND D I S CU S S I ON

Wedge crack extension measurements to evaluate adhesive bond durability areexpressed either as crack growth during the exposure test period (Aa), orinitial crack length plus growth (a +Aa). The crack growth method is satis-factory for pretreatment process control when only one pretreatment, onemanufacturer and one adhesive system are involved. In a program involvingseveral bonding facilities, however, bonding process variations, as well assurface pretreatment effects, contribute to wedge extension crack growth rates.Differences in initial crack openings for the same adhesive system areattributed to bonding process variations among the nine airframe manufacturersas well as surface pretreatment effects. Short initial crack openings that showhigher strength bonded joints may be due to surface roughness, but do not reflectdurability of prebond treatments of the titanium adherends. The shorter crackopenings must withstand higher opening mode stresses at the crack tip than longertotal crack openings regardless of growth during the exposure period. In addi-tion, some pretreated surfaces started to deteriorate during the period betweenbonding and testing of specimens even though the test program was conducted tominimize the effect of premature failure. To offset these bonding variations,total crack length is also considered as an indication of pretreatment durability.Performance of the various surface pretreatments are discussed both in terms ofconventional growth rates (a) and total crack openings (a +6a). Wedge specimenbondline fracture surfaces are also discussed and illustrated. Strain energyrelease rate curves are given for selected wedge specimen sets.

CRACK GROWTH RATES

Crack extension growth rates (Aa) of prebond surface treatments with the350 F cure FM300K/BR127 adhesive system (WI) exposed one hour to 140 F, 100% R.H.condition ranged from only 0.01 inch for the 10 volt chromic acid anodize withfluoride pretreatment (CAIO-4) to 1.74 inches for the VAST pretreatment (VA-7).After 56 days exposure this range increased to 0.09 inch for CAIO-4 specimensand 2.35 inches for VA-7 specimens. Curves of crack growth rates for the 56 dayexposure test period separate into three groups as shown in Figure 4. The threephosphate fluoride pretreatments (PF-l, PF-3, and PF-4) along with the VASTsurface preparation (VA-7) resulted in extremely high crack growth rates. DP-2and DA-5 pretreated specimens had moderately low growth rates while extremelylow growth rates were the result of CAl0-4, CA5-4, TU-8, AP-9, and LP-6 pre-treatments.

Pretreatment crack growth rates with the 250 F cure FM73M/BR127 adhesivesystem (W2) arbitrarily divide into two groups as shown in Figure 5. All PF-4and VA-7 pretreated specimens failed within the first hour of exposure and thePF-3 specimens had an average crack growth of 1.59 inches after only one hour.There were no PF-1 pretreated specimens returned for evaluation with theFM73M/BR127 adhesive system. The other seven pretreatment results were closelygrouped at the end of the 56 day exposure period. Crack growth ranged from0.28 inches for the Dapcotreat 4000 pretreatment (DA-5) to 0.44 inches for boththe chromic acid anodize pretreatments (CA5-4 and CAIO-4).

5

4.0 iNADC-82032-60

w WI- BR-127/FM-300K ADHESIVE SYSTEM

zT. 8.0

Z VA-?

ra 2.0 p-z

wS1.0

010 2 so 40 so so

EXPOSURE TIME. DAYS AT 140F, 05-100% R.H.FIGURE 4. CRACK GROWTH RATES FOR TITANIUM BONDING PRETREATMENTS

(4.0Lu W2- 8R4127/FM-73 ADHESIVE SYSTEM

0

8. pp-~ ALL FAIL110 pp-s

;j0

w

GAS&CA16-4OP-S&AP0

10 s0 so8 40 so Go

EXPOSURE TIME, DAYS AT 140F. 95-100% R.H.

FIGURE 5. CRACK GROWTH RATES FOR TITANIUM BONDING PRETREATNENTS

6

NADC-82032-60

Data for the pretreated specimens bonded with the other 350 F cure adhesivesystem, Metlbond 329/Metlbond 329 Type II Primer (W3) also separated into threegroups after exposure testing. As shown in Figure 6 all PF-1 pretreatedspecimens failed within 14 days and the PF-4, PF-3 and VA-7 treated specimenshad crack growth lengths of 1.73 to 1.81 inches after 56 days exposure.

4.0

w ,W3-! METLBOND 329 TYPE II PRIMER iXT I . %

0_; METLBOND 329 ADHESIVE SYSTEM

2.0 PF-1 (ALL FAILED)

.- VA-

WI

0

rE" , .: : :CA6-4

10 so 80 40 50 so


FIGURE 6. CRACK GROWTH RATES FOR TITANIUM BONDING PRETREATMENTS

Dapcotreat 4000 (DA-5) was the only pretreatment placed in this arbitrary middlegroup with an average crack growth of 0.73 inches after 56 days exposure. Inthe same test period the other six pretreatments had crack growths ranging from0.35 inches for the 10 volt chromic acid anodize (CA10-4) to 0.49 inches for boththe liquid hone Pasa Jell 107 (LP-6) and alkaline peroxide (AP-9) pretreatments.

Pretreatments bonded with the 250 F cure BR1271BA9628H adhesive systemare divided into two groups based on crack growth test results as shown inFigure 7. All PF-I pretreated specimens failed before or during the first hourof exposure testing. After 56 days PF-4 and VA-7 had respective crack growthsof 2.73 and 2.81 inches. The moderately low crack growth pretreatments wereDA-5, DP-2 and TU-8 with crack growths after 56 days of 0.59 to 0.63 inches. Theremaining five pretreatments had low crack growth rates of 0.30 to 0.42 inchesafter 56 days exposure.

I7

NADC-82 03 2-60

to 4.0wjW - B -2/A88 DEIESSEW4 R17EB2H DEIESSE0

z PP-u (ALL FAILED'DVEINO WEDGE INSERTIOUN9 .0

is2.zw

S1.0 o DA-6,DP-8&TU-8

AP-S&PP-8O LP-6

CA10-4

10 so so C0Aso s


FIGURE 7.* CRACK GROWTH RATES FOR TITANIUM BONDING PRETREATMENTS

The poor and marginal surface pretreatments show continued crack growththroughout the 56 day test period with the 350 F cure adhesives, FM300K and 14329.Crack growth stopped, or was minimal, after 7-14 days exposure for most pre-treatments with the 250 F cure adhesives, FM73M and EA9628H. Combining crackgrowth (Aa) data of the four adhesive systems gave the following durabilityrankings of the titanium pretreatments:

CA10-4 Most Durable

CA5-4

TU-8

LP-6

AP-9

DA-5

DP-2

PF-3

PF-4

VA-7 Least Durable

PF-1

8

NADC-82032-60

rOTAL CRACK OPENINGS

Total crack length measurements (a+a) of the eleven pretreatments with the350 F cure adhesives after 24 hours exposure are shown in Figures 8 and 9.

%VN TETMASO AMSR A ...AiIN 4"UROOT

a.. M Wffe sm m I 49 DE N MO]L RC

SYTMATR4"USEXOUET 1 40 . 1

I a.M S"T oq-A MO ri.a

I lI

- li.4. .. -

i 9.i77

lVITIM AFTM 14 MOfuI60 TO t4F, MOO MAH

FIGURE 8. WEDGE TEST RESULTS OF 3R12?/F 00K AFTER24 HOURS EXPOSURE to 140 F, 1002 of R.H.

I9

IA.:

i FIGURE 9. WEDGE TEST RESULTS OF ) IL3OND 329" TYPE 11/329

AFTER 24 HOURS EXPOSURE TO 140 F, 100O R..

,m i 9

NADC-82032-60

The liquid hone- Pasa Jell 107C pretreatment (LP-6) provided the lowest 24 hourcrack opening with the FM300K adhesive, while the Turco 5578 (TU-8) method hadthe lowest total crack opening with the M329 adhesive system. Both of these pre-treatments retained lowest average crack openings with the same adhesives after56 days exposure. The LP-6 pretreatment also gave lowest total crack lengthresults with the FM73M adhesive, while the chromic acid anodize pretreatment(CA5-4) was most effective with the EA9628H adhesive system. Total crackopening measurements (a+Aa) with all four adhesives after 56 days exposuretesting are listed in Table I.

TABLE I. CRACK OPENING MEASUREMENTS

FM300K/BRI27Prebond 56 Day Total Crack STD.

Treatment Initial Crack Length, in. Dev.ID Crack, in. Growth, in. x s

LP-6-W1 2.05 0.27 2.32 * 0.05TU-8-W1 2.14 0.22 2.36 * 0.19CA5-4-W1 2.24 0.17 2.41 0.08CAIO-4-Wi 2.34 0.09 2.43 .14AP-9-W1 2.27 0.26 2.53 0.07DP-2-W1 2.21 0.64 2.85 0.15DA-5-WI 2.33 0.63 2.96 0.10PF-4-W1 2.27 1.60 3.87 0.15PF-1-W1 2.26 1.90 4.16 0.14

PF-3-WI 2.24 2.47 4.71 0.48VA-7-WI 2.38 2.25 4.63 0.14

FM73M/BR 127Prebond 56 Day Total Crack STD.

Treatment Initial Crack Length, in. Dev.ID Crack, in. Growth, in. x s

LP-6-W2 2.03 0.31 2.34 * 0.06TU-8-W2 2.05 0.30 2.35 * 0.09DA-5-W2 2.09 0.27 2.36 * 0.07CA5-4-W2 1.94 0.44 2.38 * 0.05CAIO-4-W2 1.95 0.44 2.39 * 0.14AP-9-W2 2.04 0.38 2.42 * 0.15DP-2-W2 2.09 0.38 2.47 0.12PF-3-W2 1.76 2.29 4.05 0.15VA-7-W2 2.05 3.20 5.25 ** -

PF-4-W2 2.46 2.79 5.25 ** -

PF-1-W2 No specimens

• No significant difference in average performance basedon two-sided t-test at 95Z confidence interval.

• * Crack length extended entire length of specimens.

10

NADC-82032-60

TABLE I. CRACK OPENING MEASUREMENTS (CONTINUED)

M329/M329 Type IIPrebond 56 Day Total Crack ST.

Treatment Initial Crack Length, in. Dev.ID Crack, in. Growth, in. x

TU-8-W3 2.30 o.42 2.72 * 0.07CA5-4-W3 2.32 0.43 2.75 * 0.18CAIO-4-W3 2.47 0.35 2.82 0.04AP-9-W3 2.43 0.49 2.92 O.1DA-5-W3 2.29 0.73 3.02 0.41LP-6-W3 2.58 o.49 3.07 0.26

DP-2-W3 2.80 0.46 3.26 0.16PF-4-W3 2.43 1.73 4.16 0.18VA-7-W3 2.50 1.81 4.31 0.08PF-3-W3 2.80 2.05 4.85 0.72PF-I-W3 2.63 2.62 5.25 ** -

EA9628H/BR 127Prebond 5b Day Total Crack STD.Treatment Initial Crack Length._ in. Dev.

ID Crack, in. Growth, in. x s

CA5-4-W4 1.90 0.30 2.20 * 0.02LP-6-W4 1.87 0.38 2.25 * 0.06CAlO-4-W4 1.92 0.35 2.27 0.05PF-3-W4 1.90 0.42 2.32 0.15AP-9-W4 1.91 0.42 2.33 0.06TU-8-W4 1.82 0.63 2.45 0.12DP-2-W4 1.89 0.60 2.49 0.05DA-5-W4 1.91 0.59 2.50 0.06PF-4-W4 1.86 2.73 4.59 0.29VA-7-W4 1.89 2.81 4.70 0.30PF-I-W4 5.25 ** 0.00 5.25 ** -

No significant difference in average performance basedon two-sided t-test at 95% confidence Interval.

** Crack length extended entire length of specimens.

11

NADC-82032-60

As noted in Table I there is no significant difference in average per-formance of the top two pretreatments with FM300K, M329 and EA9628H adhesiveswhen applying the two-side t-tpst at a 95% confidence interval. The top fivepretreatments with FM73M were the same based on this statistical analysis.However, there are significant differences between groups of effective and ofpoor pretreatments. Table II lists pretreatment averages of crack measurementscalculated from combined results with all four adhesive systems.

TABLE II. COMBINED AVERAGES WITH ALL FOUR ADHESIVES

Average ofPrebond 56 DayTreatment Total Crack

Ranking ID Length, in. *

1 CA5-4 2.44

2 TU-8 2.47

3 CA10-4 2.48

4 LP-6 2.50

5 AP-9 2.55

6 DA-5 2.71

7 DP-2 2.77

8 PF-3 3.98

9 PF-4 4.47

10 VA-7 4.72

11 PF-1 4.89

• Combined average of specimenswith all four adhesive systems.

Even though the total crack length method (a+Aa) is preferred, the only change inperformance ranking from the crack growth method (A&) was among the top threepre treatments.

All wedge test data collected in this program is listed by pretreatment inTables III through XIII. Initial crack opening length (a), crack growth aftereach test period (Aa) and bondline thickness measurements are given for eachspecimen.

12

NADC-82032-60

A ;J

ca

Nw

*a N

IL.

13

NADC-82032-60

X, I M%1 fI-aa I 4

4 II

.44

a-.*

-0 Q

0.4 lw

41

00

NADC-82032-60

I t

J-4 a.

1*- 1z~

-Im

LL1

NADC-82032-60

"I" INN

nA I. - -

12 =1 -III

I ix

a W

ZI,-. ~~. -h tt~

ILI

q.

E-4

- ~ -.. N~.. .L -I' ~-16

NADC-82032-60

-. 41"

'A a.

___ 17

NADC-82032-60

~~iI*

=4,

L) It

'-4

I; IIII

-4 04#

NADC-82032-60

.. I P4

' 0

I. CO I-*INV

ra

A_ _

A;

o= '~ * .'. . . .

19

NADC-82032-60

14 j

ME;

1.44,

IN 01Z I-

22

NADC-82032-60

'IN

'ue 0% IS - %

25~ a ,.l%

l

*-c

in

ul a

Ii 21

HADC-82032-60

Ic

4. w

A -6

I:bII%

'0~ . -22

NADC-82032-60

-- I%

0-i A 0-e it -I

Q IL 'n

I 23

NADC-82032-60

WEDGE TEST FRACTURE MECHANICS

Crack growth data is more useful for comparison to other studies whenconverted to strain energy release rate values. The strain energy release rateGI (in.-lbs./in.

2 ), also called the crack extension force, is the apparentforce at the wedge specimen crack tip due to an opening mode stress. Basicwork by Ripling and Mostovoy (reference(d) and (e)) led to an equation for Gicalculations for bonded uniform double cantilever beam (DCB) specimens. Theresultant strain energy release rate formula with parameter values for wedgespecimens used in this study is as follows:

y2 Mh3 (3 (a+O.6h) 2 + h2 )GI16 ((a + 0.6h) 3 + ah 2 ) 2

Where:

GI = Strain Energy Release Rate, in.-lb./in. 2

y = Displacement at Load Point, Inches = 0.125 in.

a = Distance from Load Point to Crack Tip, Inches

h = Height of One Beam, Inches = 0.150 in.

M = Modulus of Adherend, lb./in.2 = 16,500,000 lb./in.

2

Efforts by Marceau and others (references (f) to (h)) resulted in thedevelopment and application of the thin adherend DCB specimens, or wedge testspecimens, to control adherend surface quality for adhesive bonding. The wedgetest method is good for qualitative determinations, but not used for quantitativestudies because of plastic deformation of thin metal adherends. However, thestrain energy release rate calculation is an effective method to show apparentforce at the crack tip. Figures 10 and 11 are plots of uncorrected G, values asa function of exposure time. No attempt was made to adjust strain energy releaserate values of the 0.150-inch thick titanium adherends due to the complexity ofplastic deformation rates. Calculated values are higher than actual strainenergy release rates with an increasing differential between calculated andactual rates at longer exposure times. It is apparent from the above plots thatliquid hone Pasa Jell, 10 volt chromic acid anodize and alkaline peroxide pre-treatments have much higher strain energy release rates (calculated or actual)than the PF-l phosphate fluoride pretreated with both FM300K and FM73Madhesive systems.

* I 24I-

NADC-82032-60

00

2 4* o

0

2 ~ ~ 442

aw 0 a

_ _ _ _ _ _ _ _ _ _ _ _ _ 0 U0 I

00

22

NADC-82032-60

0 *4

Ic o 0

z Zi ww J IL

w r) asa

IL I--4oW 40

0 a xv LU o

w 4 w40

wW w

Z r

w

c'x w

004

CC

z I

W z

26

NADC-82032-60

FRACTURE SURFACES

The initial fractures that result from driving the wedges into the specimensare cohesive failures through the adhesive layer as shown in Figures 12 and 13.When exposed to 140 F, 1OOZ R.H. conditions, the cracks transition into adhesivedebonding as shown with the phosphate fluoride pretreatment (PF-1) in Figure 12.

PF-1-W1-SA PF-I-WI-IA

TITANIUM WEDGE SPECIMENS WITH AS MACHINED EDGESDR127 PRIMERIFMSOOK ADHESIVE SONDMNE

AFTER 24 HOURS EXPOSURE TO 140F. 100% R.H.

FIGURE 12. TITANIUM WEDGE SPECIMENS WITH AS MACHINED EDGES

The 7.5X and 32X magnification views of specimen PF-l-Wl-3A both show the co-hesive failure mode caused by wedge insertion. This cohesive failure zone isapparent from the left edge of the photos to the vertical scribe mark.Cohesive failure is shown in the 20X magnification of specimen PF-l-WI-lA, buttransitions into a classic adhesive failure debond in the 30X magnification viewat the initial crack tip mark. Figures 13 and 14 show initial cohesive fracturefollowed by adhesive failure growth with other pretreatments and adhesive systems.The wet ground-dry belt sand finish method as shown in Figure 3 can be observed

on specimen edges in Figures 13 and 14. The wet ground-dry sand preparationtechnique provides distinct adhesive/metal interfaces on specimen edges andsimplifies crack tip determinations since adhesive failures followed along theseinterfaces.

27

NADC-82032-60

LP-6-W2-4B DP-2-W2- 18 TU-8-W2-2A

-- -77

TITANIUM WEDGE SPECIMENS

FIGURE 13. WEDGE SPECIMENS OF BR127/FM73 AFTER 24 HOURSEXPOSURE TO 140 F, 100% R.H.

28

NADC-82032-60

CA 1O-4-W3-SA DA-5-W3-3A rU-S-wa-m

01MI ox lox

-- EulTITANIUM WEDGE SPECIMENS

FIGURE 14. WEDGE SPECIMENS OF METLBOND 329 TYPE 11/329AFTER 24 HOURS.EKPOSURE TO 140 F, 100% R.H.

Initial cracks plus growth after 96 hours test exposure are shown in themontages of Figure 15 and illustrate crack growth rates for PF, DA and LPpretreatment processes.

WA-l-Wl-PA

Room=!o ..WNC

&MAit 01 AGMUUMY OISI 1W"A"M O# INT"M

W50 os I 01 A6C 4 06 IOUS - to~ 1 "C. am~

FIGURE 15. MONTAGE OF CRACK EXTENSION IN WEDGE SPECIMEN

29

NADC-82032-60

Specimens were split open after completion of the 56 day exposure periodfor failure mode analysis. Figures 16 through 26 are photographs of openedwedge specimen sets of all eleven pretreatment processes bonded with theBR127/FM300K adhesive system. Observe that wedge crack growths during exposureare mostly adhesive failure as shown in the center sections of opened specimens.The bottom sections of specimen halves show resultant cohesive fracture surfaceswhen specimens were split open after the 56 day exposure test period.

FIGURE 16. OPENED WEDGE SPECIMENS WITH PF-I PHOSPHATE FLUORIDE PAMODIFIED PRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

30

NADC-82032-60

FIGURE 17. OPENED WEDGE SPECIMENS WITH DP-2 DRY HONE PASA JELL107C PRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

FIGURE 18. OPENED WEDGE SPECIMENS WITH PF-3 PHOSPHATE FLUORIDE/HNO (NITRIC ACID) PREDIP PRETREATMENT AND BR127/FM300ICADHiSIVE SYSTEM

31

NADC-82032-60

II

FIGURE 19. OPENED WEDGE SPECIMENS WITH PF-4 PHOSPHATE FLUORIDEPRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

FIGURE 20. OPENED WEDGE SPECIMENS WITH CA5-4 CHROMIC ACID ANODIZE/FLUORIDE5 VOLT PRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

32

NADC-82032-60

FIGURE 21. OPENED WEDGE SPECIMENS WITH CAIO-4 CHROMIC ACID ANODIZE/FLUORIDE10 VOLT PRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

FIGURE 22. OPENED WEDGE SPECIMENS WITH DA-5 DAPCOTREAT 4023/4000PRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

33

NADC-82032 -60

FIGURE 23. OPENED WEDGE SPECIMENS WITH LP-6 PASA JELL 107C -WET

HONE PRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

FIGURE Ts OPENED WEDGE SPECIMENS WITH VA-7 VAST PRETREATMENTAN'D BR127/FM300K ADHESIVE SYSTEM

34

I

NADC-82032-60

FIGURE 25. OPENED WEDGE SPECIMENS WITH TU-8 TURCO 5578 PRETREATMENTAND BR127/FM300K ADHESIVE SYSTEM

FIGURE 26. OPENED WEDGE SPECIMEN WITH AP-9 ALKALINE PEROXIDEPRETREATMENT AND BR127/FM300K ADHESIVE SYSTEM

35

NADC-82032-60

Opened wedge specimens bonded with the other three adbesive systems areshown in Figures 27-29.

PF 3W2 PF AW2 Tu8W2 DfPW2 CA104. LPbW CA5AW2 AP9W2 DA SW2 VA7W2

FIGURE 27. OPENED WEDGE SPECIMENS AFTER 56 DAYSEXPOSURE BR127/FM73M

OI1.3 L-6W3 VA YW3 CA)04W3 CA5*W3 TUIW1

Figure 28A. Opened WedgeSpecimens after56 Days ExposureM329 Type I1/14329

AF9W3 D#2W3 R 3%V 004W3 DASW3

Figure 28B. Opened Wedge Specimensafter 56 Days Exposure14329 Type 11/14329

36

NADC-82032-60

VA.7-WA PF-3-W4 AP.9-W4

PP.4.Wd CAS.4-W4 DAJS.W4 CAUOD.4Wd TU.S.W4 DP.2.W4 LP.S.W4

TITANIUM SURFACE TREATMENT TREATMENT PROGRAM

CRACK EXTENSION WEDGE TEST 14V F. 100% RN

FIGURE 29. OPENED WEDGE SPECIMENS AFTER 56 DAYSEXPOSURE BR127/EA9628H

The same general failure pattern is seen on all specimens regardless of pre-treatment type or adhesive system. First is a cohesive failure zone caused bywedge insertion. Next is the crack growth zone which is predominately adhesivefailure. The crack growth zone is more extensive and dramatic with the lowdurability pretreatments. Finally, the bottom portion of each specimen exhibitsanother cohesive failure zone caused by separating the specimen halves.

* 37

NADC-82032-60

CONCLUSIONS

1. The most durable titanium pretreatment systems as determined by wedgecrack testing were chromic acid anodize with fluoride (both 5 and 10 volt),Turco 5578 alkaline etch, liquid hone Jell 107C, and alkaline peroxide.

2. Dapcotreat 4000 and dry hone Pass Jell 107M were slightly lower inoverall performance than the above five pretreatments.

3. The three phosphate fluoride pretreatments along with the VAST pre-treatment resulted in significantly longer crack growths and poorer durabilitythan the other pretreatments.

4. When using wedge tests, total wedge crack openings (a+Aa) are preferredover crack growth lengths (ta) as a measure of durability.

RECOMMENDATIONS

Pretreatment methods recommended for adhesive bonding of titanium arechromic acid anodize with fluoride, Turco 5578, Pasa Jell 107, alkaline peroxideor Dapcotreat 4000. Production experience is limited with the chromic acidanodize and alkaline peroxide processes. Alkaline peroxide solutions areunstable so stringent production controls must be used with this method. Do notuse phosphate fluoride and VAST pretreatments for titanium when high durabilityadhesive bond joints are required.

FUTURE PLANS

The alkaline peroxide process will be further developed to improve bothstability and determine effective operating ranges. The alkaline peroxide pre-treatment process provides durable adhesive bonds without treatment by solutionscontaining either chromate or fluoride chemicals and does not require anodizingequipment. Titanium surfaces prepared by the alkaline peroxide process are

relatively stable with some roughness for good mechanical bond strength.Solution temperatures up to 160 F are required, but this is below the 190-200 Ftemperature required for alkaline etch processing.

38

NADC-82032-60

REFERENCES

(a) AIRTASK No. WF61-542-O01, Work Unit No. ZM520. Standardized TitaniumSurface Treatment for Adhesive Bonding.

(b) Wegman, R. F., Levi, D. W., Garnis, E. A. and Adelson, K. M., "Durabilityof Titanium Surface Treatment for Adhesive Bonding," ARRADCON TechnicalReport ARSCD-TR-82XXX, Dover, NJ, 1982.

(c) Naval Air Systems Command Contract Nos. N00019-79-C-0294, N00019-80-C-0508and N00019-81-C-0355, Bondability of Titanium Adherends.

(d) Ripling, E. J., Mostovoy, S., and Carten, H. T., "Fracture Mechanics:A Tool for Evaluating Structural Adhesives," Journal of Adhesion, 1971,Vol. 3, pp 107-123.

(e) Naval Air Systems Command Contract No. N00019-71-C-0329, Final Report"Fracturing Characteristics of Adhesive Joints," Mostovoy, S. andRipling, E. J., MRL, Inc., 1972.

(f) Marceau, J. A., and Scardino, W. M., "Durability of Adhesively BondedJoints," Boeing Company Interim Report AFML-TR-75-3, February, 1975.

(g) Marceau, J. A., and Mc Millan, J. C., "Exploratory Development onDurability of Adhesively Bonded Joints," Boeing Company Final Report

AFML-TR-76-173, October, 1976.

(h) Marceau, J. A., Moji, Y., and Mc Millan, J. C., "A Wedge Test forEvaluating Adhesive Bonded Surface Durability," Adhesives Age, Vol. 20,No. 10, October, 1977.

I9

D IS T RI B UTIO0N L IS T

REPORT NO. NADC-82032-60

AIRTASK WF61-542-001

Work Unit No. ZM520

No. of Copies

NAVAIR (AIR-950D) .. .. .... .. . .. ... . . . . . . 13(2 for retention) (1 for*AIR-5115)(1 for AIR-320) (I for AIR-530)(1 for AIR-4103) (I for AIR-5302)(I for AIR-4112) (5 for AIR-5304)

COMNAVAIRLANT (Code 528) . . . . . . . . .. .. .. .. . . . . 1COMNAVAIRPAC (Code 7412) ... .......... . .. .. .. I

NAVAIREWORKFAC, NAS, Alameda (NESO-342) .. .. ......... IPensacola (NESO-343) .. .. .... . . . 1Norfolk (NESO-343)............. INorth Island (NESO-344)..........Jacksonville (NESO-340). .. ...........

MCAS, Cherry Point (NESO-343). .. ...........ONR, Washington, DC................. .........ONR, Eastern/Central, Boston, A ... . .. . .. .

NRL, Washington, DC. ..... .. .. .. .. .. .. .. .. .. . 1NSWC, White Oak, Silver Spring, MD . . . . ..... .. .. . * 1NWC, China Lake, CA (Code 385) .. .. .. .. .. .. . .. .1WPAFB, OH (AFWAL/NLBC and AFWAL/MLTN) .. . . . . . . . . . . . 2U.S. Army Materials &Mechanics Research Center, Watertown, MA

(DRXO4R-LS). .... ............. . . . . . . . 1U.S. Army Aviation R&D Couuand, St. Louis, MO (DRDAV-EOA) . . .1U.S. Army R&D Coimmand, Dover, NJ (DRDAR-LCA-OA) .. . . . . . . INASA Langley, Hampton, VA (LRC-MD). .. ............ 1Advanced Structures Div., Monrovia, CA . . . . . . . . . . . .. IBell Helicopter Textron, Fort Worth, TX . . . . . .. .. .. .. .. 1Boeing Aerospace Co., Seattle, WA. .. .. .............. IGrumman Aerospace Corp., Bethpages NY. .. . ......... . 1Lockheed-California Co., Burbank, CA . . .. .. .. . .. . .1Mc Donnell Douglas Corp., St. Louis, MO . . . . .. .. .. ... IMartin Marietta Laboratories, Baltimore, MD . . . . .. .. .. . .I

Rockwell International, Columbus, OH. .. ...............Rohr Industries, Inc., Riverside, CA . . . . . . .. .. .. .. .. ISikorsky Aircraft, Stratford, CT .. ........... . . . 1Vought Corp., Dallas, TX . . . . . . . . . . . . .. .. .. .. .. 1

American Cyanamid Co., Harve de Grace, MO . . . . . . . . . . I

Hysol Div., Dexter Corp., Pittsburg, CA . . . . . . . . . . . . I

Naruco Materials, Inc., Costa Mesa, CA . . . . . . . . . . . . . 1

DTC......... 1 .......... 1

TITANIUM SURFACE TREATMENTS FOR ADHESIVE BONDING

Documents

Transcript of TITANIUM SURFACE TREATMENTS FOR ADHESIVE BONDING