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[insert consultation number] [insert non-confidential generic name of the alternative substance/mixture

or description of the alternative technology] [insert date of submission]

Submission of information on

TEMPLATE

for third party submission of information on alternatives for

Applications for Authorisation

NON-CONFIDENTIAL

Legal name of submitter(s): HEF DURFERRIT

SUBMISSION OF INFORMATION ON ALTERNATIVES (NON-CONFIDENTIAL)



2

TABLE OF CONTENTS

1. ALTERNATIVE ID AND PROPERTIES ......................................................................... 3

2. TECHNICAL FEASIBILITY ........................................................................................ 4

3. ECONOMIC FEASIBILITY ......................................................................................... 4

4. HAZARDS AND RISKS OF THE ALTERNATIVE ............................................................. 5

5. AVAILABILITY ....................................................................................................... 5

6. CONCLUSION ON SUITABILITY AND AVAILABILITY OF THE ALTERNATIVE .................... 6

7. OTHER COMMENTS ................................................................................................ 6

REFERENCES ............................................................................................................ 6

APPENDIXES ............................................................................................................. 6



or description of the alternative technology] [insert date of submission] 3

1. ALTERNATIVE ID AND PROPERTIES

This document is a presentation of a surface treatment alternative who can replace chromium

trioxide in functional chrome plating (also called Hard Chromium or HC).

It seems that the CTAC consortium has not considered the alternatives carefully and mixed

different heat treatment processes* which are well defined by ISO or EU norms. We don’t

know if it’s deliberately or not but for person skilled in the art it’s obvious that Nitrocarburizing

has not the same properties than carburizing. Carburizing does not offer corrosion resistance,

friction properties, wear resistance while Nitrocarburizing offers these skills.

*cf. Analysis of alternatives of submitted by LANXESS Deutschland GmbH §7.3 ALTERNATIVE

3: Case hardening: carburizing, carbonitriding, cyaniding, nitriding, boronizing

Alternative ID:

The name of this surface treatment is Nitrocarburizing / Oxynitrocarburizing process. It’s a

well know process for a material engineer. This 40th years old process, continually improved by

specialized companies like HEF-DURFERRIT, belongs to the thermochemical process family.

Nitrocarburizing can be done in liquid ionic atmosphere, gas atmosphere or plasma

atmosphere.

HEF DURFERRIT, world leader in liquid ionic nitriding process, has developed and optimized his

own Nitrocarburizing treatments. They are commercialized under the name CLIN (Controlled

Liquid Ionic Nitriding). CLIN treatments are thermochemical Nitrocarburizing treatments which

enrich the surface of ferrous materials with nitrogen atoms and a small amount of carbon

atoms both present in the salt (§4 for more information concerning salt of the treatment).

When an extra step of oxidation is done on the parts, the process is generally called

Oxynitrocarburizing.

CLIN includes a large portfolio of well recognized treatment names like ARCOR®, TENIFER®,

QPQ, MELONITE or TUFFTRIDE.

Properties:

The layer obtained after the CLIN process is a base material conversion (ferrous parts). It’s

not a deposition (no risk of flacking). The thickness of this conversion depends of the final

requirement but it’s typically between 1 µm and 40 µm thick.

Nitrocarburized surface

This surface treatment is an industrial process (§5) which is widely developed in many

industry sectors, including automotive & general engineering (main business activity), steel,

manufacture of printing equipment, metal precision parts or aeronautic.




4

Like Hard Chromium plating technology, CLIN technology can treat - with a high flexibility - an

important range of size, geometry and weight (part from 1g to 6T). The ability to plate inner

surfaces of parts is also present with CLIN process. It’s not an electrochemical treatment

process so his homogeneity on specific geometry of part is undisputable.

Properties on parts:

Nitrocarburizing treatment (CLIN) provides a range of desired properties to the finished parts.

It enhances wear resistance, surface hardness, corrosion resistance and tribological

properties of the finished article in combination with other important functional

characteristics. His resistance under heavy charges is well known for a person skilled in the

art.

2. TECHNICAL FEASIBILITY

A quick presentation of nitrocarburizing success stories in front of Hard Chromium seems the

best way to present the technical feasibility of the nitrocarburizing treatment. Hereunder a few

examples:

Automotive and general engineering:

- Gas spring cylinders rods : 100% replaced (CLIN process: >100M parts/year)

- Wiper shafts : 100% replaced (CLIN process : >40M parts/year)

- Engine Valves : 70% replaced (CLIN process : >200M parts/year)

- Articulation joints : Industrialized (CLIN process : 4000 T/year)

- Brake pistons calipers : Industrialized at a large scale

- Shock absorbers : Industrialized at a large scale

- Steering ball stud: Industrialized at a large scale

- Differential components : Industrialized at a large scale

- Piston rings : Industrialized at a large scale

- Power train components : Industrialized at a large scale

Steel:

- Rollers and rolling mill bearings: Industrialized at a large scale

- Forging dies : Industrialized

Manufacture of printing equipment:

- Mandrels: Industrialized at a large scale

3. ECONOMIC FEASIBILITY

CLIN process price, for a same volume of production and same application, is at a similar price

level or lower than Hard Chromium plating.



or description of the alternative technology] [insert date of submission] 5

4. HAZARDS AND RISKS OF THE ALTERNATIVE

This schema presents a line of liquid ionic nitriding process (CLIN):

CLIN process line

Products used during CLIN process steps:

1) Preparation step (Degreasing): Alkaline degreasing bath.

2) Nitrocarburizing step (salt):

- Bath containing cyanate (CNO-) & carbonate (CO32-)

- Periodic regeneration of the bath with amino compounds

3) Oxidizing step (salt): Bath containing hydroxide, carbonate & nitrate alkalines

In the anterior versions of liquid ionic nitriding process, salts used in the Nitrocarburizing step

were cyanide concentrated (≈ 45% CN-). Nevertheless we want to clearly underline that CLIN

liquid ionic nitriding process uses base salts that are cyanide free. HEF’s CLIN process and

more generally Nitrocarburizing processes used today respect environmental standards and

are REACH compliant.

These last 2 years, HEF has open 4 plants in Europe. This confirms that Nitrocarburizing

processes (CLIN or other technologies) have a future.

5. AVAILABILITY

Today Nitrocarburizing (CLIN) process is available in 21 countries through the HEF’s jobbing

network (hef.fr). HEF also proposes technology transfer (licencing or consumables) with more

than 350 licences worldwide.

Other companies also propose jobbing or technology transfer all around the world with other

Nitrocarburizing technologies. The availability of this alternative is manifest.




6

6. CONCLUSION ON SUITABILITY AND AVAILABILITY OF THE ALTERNATIVE

Alternatives exist to replace Hard Chromium industrial processes on a high proportion of parts

who are currently Hard Chromium plated (Functional Chromium Plating). Nitrocarburizing is

one of these alternatives offering in the meantime technical improvement (corrosion

resistance, wear resistance, surface flaking resistance…) and cost advantages.

7. OTHER COMMENTS

These documents present and support this alternative solution. HEF’s experts are at the

disposal of ECHA agency for details and/or meeting.

Article_CLIN in Industrial Heating.pdf

Improved Corrosion Resistance Obteined Through Replacement of Chromium with Nitrocaburizing.pdf

Improvement of Tribological Properties through Nitrocarburizing.pdf

Sind die Tage des Chroms gezählt - Black is so beautiful - Christian Bartsch.pdf

NB: These documents are available hereunder.

REFERENCES

Hef.fr

APPENDIXES

None

his article discusses the appli-

cation of Controlled Liquid

Ionic Nitrocarburizing (CLIN)

processes like TENIFER® and

ARCOR® to replace galvanic coatings

like chrome, nickel and zinc plating due

to excellent corrosion resistance and wear

properties. It also highlights economical

and environmental advantages of their us-

age. Due to easy handling, complex plant

equipment is not required. The process

times are rather short and allow fl exible

work without building up bigger buffer ca-

pacities for the workload.

Introduction

CLIN is a family name of modern and en-

vironmentally friendly processes for nitro-

carburizing and oxidation of steel and cast

iron. Diffusing nitrogen and carbon results

in a so-called compound layer, which

possesses a nonmetallic character. The

outstanding advantage of this edge zone

in relation to other coatings is the fi rm

compound diffused on the base material

and not applied on the surface. Therefore,

they exhibit a very good adhesion, and

crack sensitivity is clearly reduced. De-

pending upon material used, these layers

possess hardnesses from 800-1500 Vickers.

The compound layer is supported by the

underlying diffusion layer. CLIN-treated

parts offer eminent protection against

wear, seizure, galling, pitting and fatigue.

Process Characteristics

Basically, all kinds of ferrous material –

tool steels, mild steels, valve steels, austen-

itic steels, cast iron or sintered materials

– can be nitrocaburized in salt melts with-

out any special preliminary pre-treatment.

The process sequence is not complicated.

After a short pre-cleaning and preheating

in air to 350-400°C (662-752°F), the parts

are nitrocarburized in the salt melt, gener-

ally for 60-120 minutes. Treating tempera-

ture is usually 570-590°C (1058-1094°F).

In special cases, lower (480°C) or higher

temperatures (630°C) are possible. Water,

air, nitrogen, vacuum or an oxidizing cool-

ing bath are used for quenching. Thereaf-

ter, the charge is cleaned with hot water

in a cascade. For the nitrocarburizing melt,

only the following few parameters have to

be controlled:

• Chemical composition of the melt

• Treatment temperature

• Treatment time

Salt melts possess an exceptionally high

offer of nitrogen in comparison to other

treatment media. The nitrocarburizing

process starts immediately after immer-

sion into the liquid salt bath. After a few

h

c

I

p®

T

Controlled LiquidIonic Nitrocarburizing Processes as Galvanic-Coatings AlternativeDr. Joachim Boßlet – Durferrit GmbH; Mannheim, GERMANY

Danilo Assad Ludewigs – Durferrit do Brasil; Diadema, BRAZIL

It is well known that due to process characteristics – like best repro-

ducibility on a high-quality level – nitrocarburizing in ionic liquids

provides excellent resistance to wear, pitting, galling, seizure and

surface-fatigue resistance to the treated parts. However, the cor-

rosion protection is still moderate. This problem can be solved by

post heat treatment in oxidizing salt melts, producing a very thin

but compact oxide layer on the surface of the nitride layer. Com-

bined with polishing and impregnation, the oxidized parts can have

smooth, attractive black surfaces, allowing dramatic improvements

in corrosion resistance up to 1,000 hours in salt-spray tests without

losing the previously mentioned benefi ts.

IndustrialHeating.com - September 2010 55

Cyanate Nitrogen +

+ Iron

Iron nitride

Carbonate

100

800

600

400

200

0Without oxidation

Salt spray test(ASTM B117)Test duration: 816 hoursSAE 1035CL: 20µm

With oxidation

Spray duration, h

Fig. 1. Principle of regeneration

Fig. 2. Improvement of corrosion resis-

tance by oxidizing quenching

FEATURE | Vacuum/Surface Treating

56 September 2010 - IndustrialHeating.com


minutes there is already a formation of a

compact compound layer. Industrial salts

use nontoxic sodium and potassium cya-

nate as the nitrogen source. Due to reac-

tion on the part surface, alkali cyanate

transforms into carbonate whereas the

composition of the salt melt only chang-

es slowly. The carbonate decomposition

product is recycled into active cyanate

directly within the melt by continuously

adding the nontoxic, polymeric organic

regenerator. Because there is practically

no change in volume, no bail-out salt ac-

crues from the desired adjustment of the

composition (Fig. 1).

The special characteristic of CLIN-

treated parts is the almost mono-phase

-carbonitride compound layer with very

high nitrogen content of 6-11 mass % and

carbon content of 0.5-2 mass %. At the

usual treatment times of 60-120 minutes,

the compound layer reaches 10-20 µm.

With increasing alloying proportion the

layer growth decreases.

Infl uence of Post-Oxidation to

Corrosion Resistance

CLIN-treated parts are well known for

their excellent resistance to wear, pitting

and fatigue. Furthermore, the tendency

to galling or sticking is remarkably re-

duced. Corrosion protection is only mod-

erately increased. But if parts are directly

quenched into an oxidizing salt melt and

followed by an impregnation step (if nec-

essary), corrosion resistance can be dra-

matically improved. As demonstrated in

Figure 2, the average corrosion resistance

of an SAE 1035 steel nitrocarburized part

shifted from 24 to 810 hours until fi rst

sign of corrosion was visible on speci-

mens exposed to a salt-spray test (ASTM

B117). In all cases, only single rust spots,

never larger areas, were visible when the

parts failed.

Figure 3 shows the quality of the com-

pound layer of parts, which passed the

complete test time of 1,008 hours. Besides

a slight darkening effect on the surface

and its pores, the layer itself maintained

an excellent condition. This is due to the

formation of a thin but compact mag-

netite layer (Fe3O4) on the surface and

beneath a predominantly -carbonitride

compound layer. Microsections confi rm

that the thickness of the magnetite layer

is not more than 1 µm. By using liquid

oxidizing salts as quenching media, the

top of the nitride layer is transformed into

magnetite by an exothermic reaction. If

the parts are oxidized after cooling down

to room temperature, the rise in corrosion

resistance will be lower.

Figure 4 shows the salt-spray corrosion

resistance of various galvanic processes in

comparison with TENIFER (with post-

oxidation). Even after a test period of 500

hours, no corrosion attack was visible on

the surface of TENIFER-treated piston

rods. Depending on the component ge-

ometry and roughness, resistance in the

salt-spray test reaches up to 500 hours or

more. In principle, the corrosion resis-

tance increases with decreasing surface

roughness.

Figure 5 shows the corrosion resistance

of C45 (SAE 1045) steel samples, which

underwent a total immersion test dur-

ing a period of two weeks (according to

DIN 50905, part 4), of various galvanic

processes in comparison with TENIFER

(with post-oxidation). With an average

500

400

300

200

100

0 SAE 1045 TENIFER® Cr 2 x Cr Ni

not treated 20 µm 20µm 40 µm 20 µmS

pra

y d

ura

tio

n,

h

Ferritic Nitrocarburizing

SAE 1045ARCOR® 25µm

=5 µm=16 µm

Fig. 3. Quality of compound layer after 1,008 hours in

salt-spray test

Fig. 4. Salt-spray corrosion resistance of galvanic processes in comparison with

TENIFER®

Fig. 5. Total immersion corrosion

resistance of galvanic processes in

comparison with TENIFER®

Layer or treatmentWeight loss in g/m2 per

24 hours

90 min TENIFER® 0.34

12 µm Hard chrome 7.10

Double 20 µm soft chromechrome: 25 µm hard chrome

7.20

Nickel: 20 µm Kanigen, age

hardended2.90

Triplex: 37.0 µm Copper 45.0 µm Nickel 1.3 µm Chrome

0.45

Medium: 3% NaCl, 0.1% H2O2 Material: C45 Fig. 6. CLIN-treated valves


weight loss of 0.34 g/m² per 24 hours, the

TENIFER samples resisted much better

than the electrically or chemically plated

samples. For the sample coated with 12

µm hard chrome, and even for the 45 µm

double-chrome layer, the weight loss was

more than 20 times higher in comparison

with the TENIFER-treated samples. Only

for the triplex layer (37 µm copper, 45 µm

nickel, 1.3 µm chrome) is the corrosion re-

sistance comparable with the TENIFER-

treated samples.

It is also well known that CLIN pro-

cesses, like TENIFER and ARCOR

when combined with post-oxidation in

salt melts, produce far superior corro-

sion resistance in comparison with other

nitrocarburizing processes such as gas or

plasma.

Applications

Valves in combustion engines are parts

with high thermal-stress, wear and

corrosion-resistance demands (Fig. 6).

Compared to chrome plating, the manu-

facturing costs can be reduced by nitrocar-

burizing because the induction hardening

and the fi nal grinding can be omitted. Fur-

thermore, the stem of the exhaust valve

need not be made from induction-hard-

ened steel. The valve can be completely

manufactured of heat-resistant austenitic

steel. More than 250 million valves per

year are treated in salt melts. The treat-

ment times for CLIN processes range

between 15 and 90 minutes according to

specifi cation. Depending upon plant size,

the batch size varies from 2,500-4,000

parts. A productivity of less than 1 second

per valve is thus accomplished.

Fig. 7. CLIN-treated gas spring rods Fig. 8. CLIN-treated wiper shafts

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The salt-bath nitrocarburizing in combination with oxidizing

post treatment is applied more and more for piston rods, hydraulic

cylinders or bushings. Materials such as construction steel, unal-

loyed or low-alloyed steel are used. The required holding time of the

salt-spray test is mostly 144 hours without corrosion. In some cases

the requirement is 400 hours, which is also obtained. Figure 7 shows

a gas spring piston rod, which is employed in several applications,

including the automobile and aircraft industry. By substitution of

the chrome layer, remarkable cost savings have been achieved. The

nitrocarburizing treatment is performed in a fully automated plant.

The combination of up to four nitrocarburizing furnaces within one

plant enables cycle times of 0.5-0.6 seconds per piston rod.

6000

5000

4000

3000

2000

1000

0

Detriment level expressed in nano points after normalizing

For 100 cars Gas furnace Salt bath Salt bath at 15,000 km/year (3.6m3) electrically-heated gas-fi red

Fig. 9. Computer-controlled CLIN plant Fig. 10. Ecological assessment of nitrocarburizing



The driving axle of the windshield wiper was typically zinc

plated or galvanized with nickel, but corrosion problems often oc-

curred during operation. Furthermore, on galvanic-coated parts,

the helical gearing is relatively soft, so that within the service life

it tends to slip. Meanwhile, more than 50 million of these ax-

les are CLIN treated (Fig. 8) per year and are used by almost all

leading automotive manufacturers. The thread has a better torsion

resistance, which allows the counter nut to be tightened with a

higher torque. Depending on the construction and end customer,

the corrosion resistance is up to 400 hours in the salt-spray test.

The nonmetallic character of the nitrocarburizing layer also leads

to a lower friction coeffi cient at the run of the axle within the

aluminum housing. As a result of the high nitrogen available in

the salt melt as well as the robustness of the processes, better and

more consistent results are achieved under production conditions

as compared with other nitrocarburizing processes.

Plant Technology

Meanwhile, it is understood that the heat treatment in liquid salts

can be performed in automated, computer-controlled plants. For

this purpose, there are open and capsule plants available. The au-

tomatic plant shown in Figure 9 is placed in a production facility

and treats serial parts for in-house production. A striking feature

of this plant is the spotless working environment.

Due to short treatment times, there is no need to create big

buffer capacities. The loading of the jigs is performed directly at

the machining center. The computerized control system allows

the on-line control of the parameter as well as complete batch

documentation. Labor costs are reduced to a minimum.

Among loading and unloading and input of the batch data, the

user has only to empty the fi ltration device once or twice a week

and to fi ll up the operating supplies. The plant component is pro-

vided with a computerized fi lling level control, which notifi es the

user to top up when necessary. The refi lling of the salt is performed

outside of the capsule in a special apparatus so that the operator

has neither to interfere into the heat-treating process nor to work

directly at the furnace.

It should also be mentioned that the plant is run waste-water

free and is featured with effi cient exhaust-air purifying equipment.

The prescribed limit values of harmful substances are below speci-

fi cations. Therefore, there is absolutely no problem of getting au-

thorization for starting new plants.

In addition, an ecological assessment of nitrocarburizing, pub-

lished by the University of Bremen in 2001, found that from an

ecological point of view salt-bath nitrocarburizing (CLIN) is more

favorable than gas nitrocarburizing (Fig. 10). If the study is consid-

ered objectively, the opinion often expressed that salt-bath tech-

nology harms the environment and, therefore, does not conform

to present-day environmental philosophy, cannot be confi rmed.

Conclusion

CLIN is, in most cases, the ideal alternative for galvanized layers,

for distortion-affl icted hardening processes and for gas or plasma

nitrocarburizing processes. Applications are also increasing as an

alternative to expensive corrosion-resistant steels.

On the basis of the following specifi c process characteristics,

CLIN processes offer excellent reproducibility on a high-quality

level.

• No complex pre-cleaning necessary

• Homogeneous and very large offer of nitrogen in the entire melt

• Quick and constant heat transfer

• Only few process parameters are to be considered

• Structure and density of load has only minor effects

• Simple, automatable process engineering

The results achieved under test conditions can usually be easily

transferred into series production. IH

The TENIFER® process is known in Europe and German-speaking coun-

tries under that name, in English-speaking and Asian countries as

TUFFTRIDE®, and in the U.S. as MELONITE®. TENIFER®, TUFFTRIDE® and

MELONITE® are registered trademarks of Durferrit GmbH. ARCOR® is a

registered trademark from HEF France (CENTRE STEPHANOIS DE RE-

CHERCHES MECANIQUES HYDROMECANIQUE ET FROTTEMENT).

For more information: Dr. Joachim Boßlet, Durferrit GmbH,

Mannheim, Germany; e-mail: [email protected]; web: www.

durferrit.com or Danilo Assad Ludewigs, Durferrit do Brasil, Diadema,

Brazil; e-mail: [email protected]; web: www.durferrit.com.br


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