CN1020762C - Infultrant for solid rare-earth chemico-thermal treatment - Google Patents

Abstract

The present invention is prepared by the method that rare earth chloride, rare earth fluoride, rare earth carbonate and rare earth nitrate are used as main energizers, and a small amount of other promoting compounds is added to the main energizers. The present invention can be widely used for solid carburizing, drip feed type gas carburizing, carbonitriding, soft nitriding, and multicomponent co-infiltrating process of carbon, nitrogen, boron, sulfur, etc. The present invention can be used for treating carburizing steel, structural steel, tool steel and die steel. Rare earth energizers are added to the present invention, and therefore, an infiltration rate can be increased by 15 to 25%. A metallographic structure is improved, use performance is enhanced. The present invention has obvious technical economic benefit, and is an ideal energizer at present.

Description

The invention relates to a solid-state rare earth chemical heat treatment infiltration catalyst.

Rare earth chemical heat treatment is a new field of rare earth application developed by the inventors in recent years. Including the application in the process of infiltrating metals such as boron, vanadium, silicon, chromium, chrome aluminum, vanadium boron, etc. Rare earth plays two important roles in the above chemical heat treatment process. One is the activation and infiltration effect, such as increasing the infiltration speed in carburizing and carbonitriding; The medium rare earth elements themselves have also been infiltrated into the surface of steel parts, which can improve the metallographic structure and properties of the infiltrated surface layer. For example, in the process of carburizing or carbonitriding, the concentration of carbon and nitrogen infiltrated into the surface layer can be increased, and the number of carbides can be increased. And refinement, so that the wear resistance, corrosion resistance, fatigue and contact fatigue strength are improved.

It also plays a similar role in boronizing, chromizing, boron-vanadium, and chrome-aluminum co-infiltration. Therefore, the application of rare earths in the field of chemical heat treatment has very broad prospects.

In the prior art, the rare earth element in the rare earth infiltration agent generally adopts mixed rare earth chloride, rare earth carboxylate or naphthenic rare earth, as disclosed in Chinese patents 85100594 and 87101329, and the infiltration agent made of the above-mentioned rare earth Its infiltration effect is relatively obvious, and it can generally increase the infiltration rate by 15-25%. However, due to the small amount of rare earth elements infiltrated into the surface of steel parts during the infiltration process, the microalloying effect is not ideal, and generally available The tensile strength of steel parts reflects the effect of microalloying from the side. For example, the tensile strength of No. σ _b =112 kg/mm ² .

The object of the present invention is to provide a solid-state chemical heat treatment rare earth infiltrating agent and its preparation method. By using the infiltrating agent, not only a higher infiltration effect can be obtained, but also a better microalloying effect can be obtained.

Main points of the present invention are as follows:

1. The composition ratio of solid rare earth permeation agent is: 10-40% of rare earth chloride L _a or C _e rare earth salt, 50-60% of sodium carbonate and barium carbonate, 10-20% of urea, 15-20% of sodium acetate, of which Chloride La or _Ce can also be replaced by mixed and elemental La and Ce fluoride salts, nitrates or carbonates. When used for solid carbonitriding, add 20-30% of yellow blood salt, the other The preparation method is to use syrup and starch as a binder to uniformly mix with the above-mentioned ingredients, and then extrude into 4-8mm granules.

The solid rare earth permeation agent proposed by the present invention is suitable for:

1) Solid rare earth infiltration catalyst is suitable for solid carburizing and carbonitriding.

2) Liquid rare earth permeation agent is suitable for dripping gas rare earth high and medium temperature carburizing (RE-C), rare earth medium temperature carbonitriding (RE-C, N), rare earth low temperature nitrocarburizing (ie soft nitriding RE-N, C), medium and low temperature rare earth carbon nitrogen boron (RE-C, N, B) and low temperature rare earth nitrogen carbon boron sulfur (RE-C, N, B, S) and other processes.

The following rare earths used in the solid rare earth penetrating agent of the present invention are all effective: rare earth chlorides comprising simple La and Ce; fluorides of mixed rare earths and simple La and _Ce ; nitric acid of mixed rare earths and simple La and _Ce Salt; and carbonates of mixed rare earths and elemental La and _Ce , etc. These compounds are all soluble in alcohols such as methanol, ethanol, and isopropanol.

According to the different requirements of solid carburizing and dripping multi-component gas infiltration (RE, C, N, B, S, etc.), different rare earth infiltration catalysts are prepared. The rare earth penetrating agent of the present invention is a universal type, and the so-called universal type refers to the situation that the original process parameters and the penetrating agent are basically unchanged. At the same time, adding the rare earth penetrating agent of the present invention can achieve the purpose of ① increasing the penetration rate by 15-25%; ② improving the metallographic structure and performance.

Solid carburizing is an ancient chemical heat treatment technology, which is still used in many factories. The solid carburizing agent in the world and in my country has been commercialized, and it is very convenient to use. However, the carburizing agents currently available in the market still have the disadvantages of high carburizing temperature and long carburizing time, which make the grains of the processed product coarse, deteriorate the performance, and consume a lot of energy. This situation urgently needs to be improved.

In the present invention, under the condition of keeping the original carburizing agent completely unchanged, an additional infiltration accelerator is developed by utilizing the infiltration effect of rare earth. When solid carburizing, as long as a small amount of solid rare earth infiltrating agent of the present invention is added in a certain proportion according to the weight of the original carburizing agent, obvious effects can be obtained, and the carburizing speed can be increased by 15-25%, or The carburizing temperature can be reduced from 920 to 940°C to 880°C. Thereby reducing energy consumption and improving the organization and performance of processed workpieces.

Adopting the solid rare earth penetrating agent of the present invention has the following advantages:

1) Fast permeation speed Adding rare earth permeation agent is 15-25% faster than without adding it, which improves labor productivity;

2) The quality of the infiltration layer is high. Since the rare earth can penetrate into the surface of the steel part, it can improve the surface structure and performance, such as the morphology, quantity and distribution of the second phase compound, and improve the anti-wear, anti-corrosion and anti-fatigue properties;

3) Energy saving Statistics show that energy can be saved by 10-15%;

4) Applicable to a variety of processes and equipment;

5) Stable and reliable quality, high reproducibility.

Example:

1. Solid rare earth penetrating agent: 20% La chloride, 25% sodium carbonate. 30% barium carbonate, 10% urea, 15% sodium acetate, carry out solid carburizing on the 20# steel axle block, the original process uses the purchased charcoal carburizing agent to pack, carburizing at 920 ℃, the required layer depth is 0.5-0.8mm to Put into the furnace for 6 hours after heating, σ _b = 112kg/mm ² , use the above-mentioned solid rare earth infiltration catalyst for carburization, furnace temperature 880°C, and leave the furnace in 4 hours, σ _b = 133kg/mm ² .

Claims (6)

1, a kind of solid-state rare-earth energizer, the composition that it is characterized in that this energizer are Lanthanum trichloride or Cerium II Chloride 10-40%, yellow soda ash and barium carbonate 50-60%, urea 10-20%, sodium-acetate 15-20%.

2, energizer according to claim 1, when it is characterized in that this penetration enhancer is used for solid carbonitriding, other adds yellow prussiate of potash 10-30%.

3, energizer according to claim 1 is characterized in that using syrup, is squeezed into the particle of diameter 4-8 millimeter after starch is made tackiness agent and various uniform ingredients in this energizer is mixed.

4, a kind of solid-state rare-earth energizer, the composition that it is characterized in that this energizer are the lanthanum of blended or simple substance or the fluoride salt of cerium, nitrate or carbonate 10-40%, yellow soda ash and barium carbonate 50-60%, urea 10-20%, sodium-acetate 15-20%.

5, energizer according to claim 4, when it is characterized in that this penetration enhancer is used for solid carbonitriding, other adds yellow prussiate of potash 10-30%.

6, energizer according to claim 4 is characterized in that using syrup, is squeezed into the particle of diameter 4-8 millimeter after starch is made tackiness agent and various uniform ingredients in this energizer is mixed