DE2109997B2 - Process for surface alloying, in particular chromium-coating of ferrous materials - Google Patents

Description

The invention relates to a method for processing,

Surface alloying, in particular inchromizing of FIGS. 3 to 7, sections through surface alloyed

Ferrous materials, in which the work piece to be treated,

piece at elevated temperature with a gaseous Fig. 8 the scheme of a method for testing

Metal halide is brought into contact. the wear resistance,

Processes of the aforementioned type are known; so 35 F i g. 9 shows a graphical representation of the wear

in the DL-Patent 66 345 a process of a chain chromed in the usual way,

for chromium plating of ferrous materials, Fig. 10 is a graphical representation of the dependencies

where the hardness of the workpiece to be chromium-plated depends on the thickness of the surface alloy

next a firmly adhering, porous and metallic th zone,

Chromium in a metal-to-metal contact with the surface layer containing the 40
before it is provided with a metal halide-containing overlay.

diffuse the chromium at a temperature of Fig. 13 is a graphical representation of the wear

decomposes at least 750 ° C. With this process, strength.

Ren is therefore an iron material inchroraiert, the In the device according to FIGS. 1 and 2 is a already a, for example, galvanically applied non-oxidizing gas, for example nitrogen, ar-chromium layer owns. gon or a hydrocarbon gas through a large number of blow holes of a pipe 3 is also introduced from the German Auslegeschrift, In 11 59 238 a gas chromating process is known, which is used in the lower part of a front opening 2 of a

• with the help of which parts made of steel without a prior treatment chamber 1 with a front door 4: previous application of a coating to the upper level. This creates a preventive surface with a rust-resistant diffusion or inducing gas curtain. A workpiece 5 rests on a chrome- plating zone. Rail 6 in the treatment chamber 1, which, in addition to the invention, is based on the object of creating ^a method for surface alloying for the material 7 which produces chromium chloride. After closing the front door 4, the supply of a corrosion- and heat-resistant as well as non-oxidizing gas is interrupted and results in a wear-resistant surface zone. The solution after the air is sucked through a suction tube 8

* This task is based on the thought, in situ, being the temperature in the treatment; To generate chromium carbide. In detail, the 60 chamber is brought to about 1000 ⁰ C, so that the

Invention is that enriched with chromium chloride in the aforementioned chamber atmosphere. The process also takes place at the treatment temperature for 5 hours, while chromium diffuses into the upper temperature, decomposing hydrocarbons into the gaseous phase surface of the workpiece 5 and results in a chrome, cemented zone on the basic structure A (Fig. 3

In the method according to the invention, this becomes 65 to 7).

Workpiece initially gas-chromed in the usual way, instead of the material 7 which emits chromium chloride

A finely divided metal halide can be made of a chromium-iron alloy through an opening T

To generate surface zone, the chromium content of which are genid introduced into the chamber 1.

3 4

During chrome plating, for example, steel with 0.025% C, 0.25% Si, 0.8% Mn, G, 1 to 5 percent by volume methane or propane gas 0.011% P and 0.025% Sgas are chrome-plated
introduced through a feed pipe 9 in order to produce carbon rn by thermal decomposition, the amount 150 kg (70 pieces)

converts with the halide to chromium carbide and to 5 per operation

chrome-plated zone B has a chrome-plated chrome temperature of 1000 ° C

carbide containing zone C results. Duration 5 hours

A cooling time of 2 hours is then passed through the feed pipe 9

non-oxidizing gas, for example nitrogen or

Argon or hydrocarbon gas, in the handling ίο The treated workpiece had a diffusion chamber 1 introduced and at the same time the iron zone of 18 μm thickness and was characterized by a high gloss, suctioned off chloride (FeClJ-containing atmosphere, without a chromium plating up and through the non-oxidizing agent Gas was replaced, as illustrated in Fig. 4. The work before the workpiece was transferred into a cooling chamber 10 connected to the treatment piece in a corrosion-resistant manner in a salt chamber 1 15 pitric acid solution.
is, a non-oxidizing gas, for example nitrogen, argon, water - Example 2
fabric or a hydrocarbon gas, introduced into the cooling chamber 10 and at the same time the ferric chloride under the following conditions, a (FeCl ₁₎ containing gas containing 10 20 gear from a chromium-molybdenum steel penetrated with from the treatment chamber 1 into the cooling chamber, 0 , 4 "" C, 0.32% Si, 0.82% Mn, 0.021 »0 P, U, 015 °, O sucked off through a suction tube 12. S, 1.02% Cr and 0.25 ° / o Mo treated.

Then an intermediate door 13 is opened and that

Workpiece transferred to the cooling chamber 10, such as quantity 150 kg (50 pieces)

is indicated by the number S '. Then the 25 per operation

Intermediate door 13 closed and the workpiece from temperature 1030 ^c C

chilled. Duration 5 hours

When the workpiece S 'in the cooling chamber 10 to

to about 300 ^c C is cooled, is nichtoxydieren- The workpiece was quenched in oil and bedes gas is injected by means of a pipe 15, which at the 3 °, a inchromierte zone of 20 μηι thickness, drawing the lower region sat a rear opening 14 of the items by high Shine and the absence of the cooling chamber 10 is arranged. The workpiece is made of chromium plating illustrated in FIG. 4; it had a Rockwell hardness of 70 at the surface chamber 10 taken out by the gas curtain that was being formed from the cooling chamber 10, so that it was exposed to air and a hardness of 52 in the core. It also drew room temperature to cool down. 35 this gear is characterized by a remarkable

The workpiece has a in FIG. 3 shown improvement of the corrosion resistance and the improvement

Structure. The chrome-plated zone B and the chrome wear resistance compared to an ordinary

Carbide-containing chromium-plated zone C is exposed over borrowed gear.

one another on a basic structure A made of ferrite or _R. . ,,

Perlite. Since the workpiece in the cooling chamber is down to 40 »e 1 s ρ 1 e 1 J

a temperature has been cooled, below which an externally smooth round stat

a detrimental influence of the ferric chloride containing dei 9.5 mm in diameter and 50 mm in length

Atmosphere no longer exists, there is no chemical composition below,
drive a chrome plating. As a result, it stands out

the workpiece is characterized by its high gloss. 45 -

According to FIG. 2 can be made of steel type in place of the cooling chamber

a quenching chamber 18 with an oil tank 17 tre- carbon- Nicdrigman- chrome-

to be able to quench the workpiece. That ^{stole I.}
Basic structure of a quenched and at 180 to

The 600 "C tempered workpiece is made of Marten- 50 Chemical

^Slt '"· .., ... - - ~. ·*, Together-

In the device according to F1 g. 2 can be a Vorsetzune (%)

hang from non-oxidizing gas in place of C 0 43 0 23 0 22

Step between door 13. Instead of chromium chloride <- q '~ \ g'jy Q21

can the process according to the invention with chromium ₅₅ «. q ', o / 35 q 72

iodide, chromium fluoride or also Tttanhalogenid, bei- ρ 0021 0019 0017

for example titanium chloride or silicon halide "0016 0020 0016

be performed. P '' j'q ·.

The front part of the device can also be marked with -J q ^ j
a gas pipe 19 to form a gas curtain 60 ° '
and a preheating chamber 21 with a front door

20 be provided to the workpieces in the chamber I _n an oven with externally controllable atmosphere

21 preheat. Sphere samples and a chromium chloride were produced

ing material introduced. After removal

When the air out of the furnace occurred, the fine particles were au;

Chromium chloride, which is partly in the melted egg

Under the following conditions, a condition became and inside the oven or on the wall cogwheel intended for a chemical machine found, aufeewirbelt. by the furnace tempe

temperature was increased to about 1000 ° C. According to un- B e i s ρ i e 1 5

About five hours of treatment became a small one

Amount of methane introduced. Finally, the one link chain of 7.1 mm normal size

Samples from Z oven heat were quenched in oil in such a way that 20.2 mm pitch and a Gheder chain were prevented from surface oxidation. The samples were then tempered at 180 to 600.degree. C. with 5 9.5 mm normal dimensions and 28 6 mm divisions. a weldable steel with 0.23% C, 0.21% bi,

The structure of sample I showed a chromium-cement 1.43 "/" Mn, 0.012 "/. P and 0.023 »/. S, zone B with a thickness of about 15 μm and a corresponding example 3 with a chromium-plated zone B chromium-chromium carbide zone · C of about 20 μm with an average of about 17, un thickness ^ and a thickness and a martensitic core. io chromium-chromium carbide zone C of average

If, on the other hand, samples II were slowly reduced in thickness in the oven and a core A made of tempered, then a chromium zone B was provided with a martensite (Figs. 3, 5). The hardness of zone C of thickness 15 (im and a chromium-chromium carbide- was greatest, the zone C had the hardness of a zone C of 20 .mu.m thick and a ferrous or iron-chromium alloy and the core the hardness of an oerlitic core A. ' (Fig. 6). ¹ S tempered martensite (Fig. 10).

After a usual inchroming at 1000 ⁰ C during quenching and tempering, the structure

Over 5 hours with slow cooling in the furnace conversion both in zone C and in the samples III with a decarburized zone D zone B and in core A the specific volume, so lus ferrite and a pick of 10 μΐη, one Chromium that, according to FIG. 11, a compressive stress in zone E with a thickness of 5 μm and a 20 μm ao of the outer zone and a tensile stress in the core thicken chromium zone F and a ferritic-pearlite. The result is a better Dauer's kernel A ' (FIG. 7). strength of the chain.

Two of the samples from this experiment were used in Example 6

Use of machine oil as a lubricant under a load of 500 kp with wear and tear. A conventional chain chain 1 from test according to FIG. 8 subjected to the 7.1 mm normal size and 20.2 mm division from one Measure diameter reduction. Steel with 0.23% C, 0.21% Si, 1.43% Mn, O, O12 «/ oP

The respective wear loss results from the and 0.023% S, as well as a according to the invention

ΐ Diagram of Fig. 9, which clearly the superior Ben process treated link chain II with un-

■ 'denotes the chromium-chromium carbide zone C and, which is approximately 24 μm thick according to the method according to the invention

?> Acted samples 1 and II can be seen. approximately 17 μm thick chrome zone. In the loose

- Hausen experiment, the chain H turned out to be an essential

A example 4 _better ^ _{5 the} usual chain I, like the curve

After samples in accordance with the course in the diagram of FIG. 12 shows

game 3 were provided with a chrome zone, 35 ».:.";", ₇

were about 10 to 200g per 100kg of coal-neispi-i

fabric powder with a grain diameter of less than 1 mm. A surface treatment by means of the usual

placed in the furnace to form chromium carbide zn. Inchromierens was purified on a link chain I of Example Samples were transit sen and cooled 3 angelas- 7.1 mm Standard size and 20.2 mm pitch ff in the furnace accordingly; they had a chrome 40 led, which was made of steel with 0.23%> C, 0.21% Si,

Chromium carbide zone on a chromium zone and a 1.43% Mn. Consisted of 0.012% P and 0.023% S. That Wear resistance like samples I and II of the structure of the chain consisted of a ferritic-pearl example 3 see core as well as a decarburized ferrite zone,

Similar results can be achieved if a chromium diffusion zone and a chromium zone, the surface zone, is carbonitrided. In each 45 the average thickness of each zone amounts to 9 to trap results in a corrosion-resistant and different 48 μm, 10 to 17 μm and 11 to 24 μm.
wear-resistant upper zone, which neither in the atmosphere

still in fresh water, sea water, nitric acid or traded tempered sample II possessed corresponding organic acids rusts. The chromium in Figs. 3 and 5 is a chromium zone B and a sufficient amount of chromium has diffused into the iron, 50 chromium carbide zone C and a core A from so that, even if a locally high load acts on the martensite, the average thickness of the workpiece, <fie mefaumierte zone with large zone B was 13 to 17 pm, which the zone C 14 bfc is prevented from detaching itself. 24 pm.

Furthermore, the value piece receives the result of wear and tear by quenching on Grand

and tempering a core of tempered Marten- 55 even with samples I and Π, the ή sit. This results in the diagram shown in Fig. 13 with increased breaking strength. Machine oil was used and the K
and before increased wear resistance is charged with 11

For this purpose 4 sheets of drawings

Claims (3)

on the treatment time and / or the chrome claims: concentration in the gas phase is dependent. Select 1. Processes for surface coating, including gas chroming, are then additional special chromium plating of ferrous materials, nor decomposes at the chromium plating temperature. J in which the workpiece to be treated slides into the gas phase when hydrocarbons are generated higher temperature with a gaseous Me- so that simultaneously with the chromium from the Halotallhalogenid is brought into contact with da- genide decomposition also a highly active carbon from characterized in that the hydrocarbon decomposition also occurs. The decomposing Zing carbon which decomposes at the treatment temperature combines with the halogenated hydrocarbons introduced into the gas phase w chromium to chromium carbide, which in turn is area zone is embedded by controlling the 2. The method according to claim 1, characterized in proportions can in the inventive by cooling the material in a non-process a desired amount of chromium carbide in oxidizing, iron halide-free atmosphere. a bedding compound made of chrome or a chrome r 3. The method of claim 2, being incorporated by iron alloy. indicates that the workpiece is quenched. piece in a cooling chamber under a non-oxidizing 4. The method according to any one of claims 1 to 3, generating atmosphere cooled or quenched. At characterized in that carbon powder can also replace the hydrocarbons with carbon the gas phase is introduced. 20 powder can be introduced into the gas phase. Except- 5. The method according to any one of claims 1 to 4, the workpiece can be characterized in that the surface rer before the surface alloy. also initially be provided with a carburized or carcone of the workpiece initially carburized or rated surface zone,
is carbonitrided. The invention is explained below with reference to 25 exemplary embodiments and the drawing of the closer explained. In the drawing shows F i g. 1 shows a longitudinal section through a device for carrying out the method according to the invention, FIG. 2 is a side view of a similar device