SU1493687A1 - Composition for complete saturation of cast-iron articles - Google Patents

Abstract

The invention relates to metallurgy, in particular, to chemical heat treatment, in particular to complex processes of diffusion saturation to increase the heat resistance and durability of cast iron products operating under conditions of variable temperatures and abrasive wear, and can be used in mechanical engineering. The purpose of the invention is to increase the heat resistance of cast iron products. The composition contains the following components, wt.%: Boron carbide 20-30

chromium powder 15-20

aluminum powder 5-10

ammonium chloride 0.5-1

sodium fluoride 2-3 and alumina else. The composition, due to the complex surface doping of cast iron products with boron, chromium and aluminum, makes it possible to increase their heat resistance by 1.5–2.0 times. 2 tab.

Description

(21.) (22) (6)

one

4227930 / 31-02

13..87

07.15.89 Null 26

(71) Kalinin Polytechnic Institute

(72) L. T. Gordeeva, N. V. Tkacheva, and I. A. Ivanov

(53) L21.785-51.06 (088.8)

(56) USSR author's certificate te 114964, cl. C 23 C 12/02.

I

(54-) COMPOSITION FOR COMPLEX IIAOTPIE-INFORMATION OF THE IRON PRODUCTS

(57) The invention relates to metallurgy, in particular to chemical heat treatment, namely to complex diffusion saturation processes to increase the heat resistance and durability of cast iron products operating under conditions of variable temperatures and abrasive wear, and can be used in mechanical engineering. The purpose of the invention is the superior heat resistance of cast iron products. The composition contains the following components, wt%: boron carbide 20-30; chromium powder 15-20; aluminum powder 5-10; ammonium chloride 0.5-1; sodium fluoride 2-3 and alumina else. The composition, due to the complex surface doping of cast iron products with boron, chromium and aluminum, makes it possible to increase their heat resistance by a factor of 1.5-2.0. 2 tab.

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(/)

The invention relates to metallurgy, in particular to chemical heat treatment, in particular to complex processes of diffusion saturation of cast iron products to increase heat resistance and durability, operating under conditions of variable temperatures and abrasive wear, and can be used in mechanical engineering.

The purpose of the invention is to increase the heat resistance of cast iron products.

The composition for complex saturation of cast iron products contains 15-20 wt.% Chromium powder, 5-10 wt.% Aluminum powder, 20-30 wt.% Boron carbide, 0.5-1 wt.% Ammonium chloride, 2 - 3 wt. % sodium fluoride and the rest alumina.

Functional purpose.

Boron carbide, chromium and aluminum powders are active components, suppliers of boron, chromium and aluminum atoms to the surface of cast iron products.

Ammonium chloride and sodium fluoride are activators of the Nascene process.

Aluminum oxide is an inert additive that prevents sintering of the saturating mixture.

The addition of boron carbide and sodium fluoride to the composition of the surface hardening of cast iron ensures good durability of parts when

1000 ° C.

The composition provides diffusion saturation of the surface of cast iron products simultaneously with boron, chromium and aluminum.

4 CO CO O5 00 vl

I pji dif) uzionny complex saturation of the surface of the parts, the first to begin its penetration aluminum. Aluminum enhances the active ability of chromium. Chromium, moving along with the reminder, sucks carbon, dissolves graphite, and binds it to carbides.

Sodium fluoride decomposes at the process temperature to form BFj. The presence of trifluoride boron in the reaction zone has an intensifying effect on the recovery of boron anhydride to lower oxide present in technical carbide boron anhydride).

A complex composition of the coating is created on the surface, which has the ability to heal microcracks of thermal origin,

An example, the technology of preparation of this composition is as follows: the components, previously dried (to remove moisture), are mixed in a certain mass percent. After that, the samples are packed in a container and filled with a saturating mixture. The finished container is placed in an oven and heated at T 900 C for 4 hours,

The compositions of saturating mixtures are given in table. 1, the characteristics of the developed compositions and the prototype in Table 2,

From t bl, 1 and 2 it follows that the best results in heat resistance when you have compounds II-IV,

Introduction to the composition of boron carbide less than 20% and more than 30%, chromium powder less than and more than 20%, aluminum less than 5% to more than 10%, ammonium chloride less than 0.5% and more than 1.0%, fluorideCarbide boron Chromium, pore Aluminum ammonium chloride

less than 2% sodium and more than 3% give a more significant increase in mass, which corresponds to greater oxidation (ia, 30.2 mg / cm, & 28 mg / cm at the test temperature compared with the optimal formulations (var, II- Iv)

The heat resistance of the cast iron hardened sample to the cleavage of the diffusion coating was 70 cycles, the known — AO cycles.

The complex surface doping with boron, chromium, aluminum creates a complex composition Aljt –j i i that has the ability to heal thermal cracks and protects the iron from corrosion to

temperatures of 1000 ° C, since these layers dissolve upon prolonged exposure to high temperatures with less intensity.

Thus, the composition provides increased heat resistance of cast iron products in comparison with the known 1.5-2-2 times.

Claims (1)

Invention Formula thirty A composition for complex saturation of cast iron products containing chromium powder, an aluminum-containing substance and aluminum oxide, ammonium chloride, 35 characterized by the fact that, in order to improve heat resistance, it additionally contains boron carbide, sodium fluoride, and aluminum powder 40 as an aluminum-containing substance. in the following ratio, wt.%: Carbide boron 20-30 Chromium powder 15-20 Aluminum powder 5-10 45 Ammonium chloride 0.5-1.0 Sodium fluoride 2-3 Alumina Rest Table 1 Properties known and proposed formulations Relative weight change (weight gain) of the sample, mg / cm, (heat resistance according to GOST 6170-73) Heat resistance under the conditions of thermal cycling (number of cycles, No.) Note: The test temperature according to GOST 6170-73 1000 C, duration 24 hours, the surface of the sample is 2.8 cm. The tests for heat resistance under the conditions of thermal cycling were carried out in an electric furnace at 1000 ° C with a holding time of 10 min, followed by cooling to water. For the criterion of heat resistance, the number of cycles (N) is accepted before the appearance of spalling, cracks visible with the naked eye. table 2 30,217 nineteen 21 28 70 70 70