CN1317407C

CN1317407C - Method for producing steel bonded carbide

Info

Publication number: CN1317407C
Application number: CNB2005100868034A
Authority: CN
Inventors: 郭志猛; 高峰; 林涛
Original assignee: University of Science and Technology Beijing USTB
Current assignee: University of Science and Technology Beijing USTB
Priority date: 2005-11-07
Filing date: 2005-11-07
Publication date: 2007-05-23
Anticipated expiration: 2025-11-07
Also published as: CN1752239A

Abstract

The present invention provides a method of preparing steel bonded carbide, which belongs to the technical field of preparing steel bonded carbide. The present invention comprises the following steps: iron oxide powder, aluminum power, tungsten trioxide powder and graphite powder are mixed according to the proportionof the reaction equation of Fe2O3+2(1+x)Al+xWO3+xC=(x+1)Al2O3+2Fe+xWC, wherein the x is from 0.5 to 3; enormous heat quantity is released after the reaction, the obtained aluminum oxide and the ion are in a molten state, and the tungsten and the carbon are melted in the molten ion; the aluminum oxide and the molten iron are separated under the action of gravity, and the aluminum oxide is floated on the upper surface of the iron; the tungsten and the carbon are combined to obtain the carbide of tungsten along with the reduction of temperature, and a large amount of the carbide of tungsten is separated from the molten iron; after the molten iron is cooled, the slag layer of oxide of the surface is removed to obtain steel bonded carbide. The present invention has the advantages of simple technology and equipment, energy saving and compact structure of the obtained product of steel bonded carbide.

Description

Preparation method of steel bonded hard alloy

Technical Field

The invention belongs to the technical field of steel bonded hard alloy preparation, and particularly provides a preparation method of steel bonded hard alloy.

Background

The steel bonded hard alloy is a composite material which takes hard compounds as hard phases and steel as a binding phase. It has the hardness and wear resistance of hard compound and the strength and toughness of steel. Has the advantages of good performances of machinability, heat treatment, forgeability, high hardness, high wear resistance and the like, and is very wide in application.

Self-propagating High-temperature Synthesis (abbreviated as SHS) is a new technology for preparing materials by utilizing Self-heat release of chemical reaction. The high temperature generated by the self-propagating reaction mixture during the combustion synthesis process exceeds the melting point of the product to form a melt, and the melt is treated by a metallurgical process to obtain a casting and a coating or complete welding, wherein the method is called SHS metallurgy. Self-propagating fusion castingis a form of self-propagating metallurgy, mainly used to prepare castings of refractory compounds,

the traditional method for producing steel bonded hard alloy mixes hard phase particles (mainly TiC, WC) with alloy powder (such as Fe, Fe-Ni, Fe-Co-Ni, Fe-Cr, etc.) of binder phase components, adopts powder metallurgy method, and is sintered in a vacuum furnace, sometimes needs proper heat treatment process. Powder metallurgy processes have advantages in adjusting composition and forming, but it is difficult to obtain fully dense materials without voids during sintering, and thus the expected material properties are not achieved.

Chinese patent 94119833.2 provides a method for preparing steel bonded hard alloy by reaction sintering, which is characterized in that graphite, boron nitride or boron carbide, nickel, molybdenum or tungsten and ferrotitanium powder containing 10-70% of titanium are pressed and formed by the traditional powder metallurgy process, and sintered in a hydrogen or vacuum sintering furnace to prepare the steel bonded hard alloy.

Disclosure of Invention

The invention aims to provide a preparation method of steel bonded hard alloy, which directly generates a hard phase and a binding phase by a self-propagating fusion casting method, improves the compactness of materials, simplifies the process and saves energy.

The basic concept of the invention is as follows: mixing iron oxide powder, aluminum powder, tungsten trioxide powder and graphite powder according to the following reaction formula, wherein x is adjustable according to the generation requirement, and the range of x is 0.5-3:

the reaction releases huge heat, at high temperature,the generated alumina and iron are in a molten state, and tungsten and carbon are dissolved in liquid iron. Alumina is separated from the liquid iron under the action of gravity, and the alumina floats on the upper surface of the iron. As the temperature is lowered, tungsten combines with carbon to form tungsten carbide, which is precipitated in a large amount in the molten iron. And after cooling, removing the oxide slag layer on the surface to obtain the steel bonded hard alloy. Because the reaction is rapid, and the alumina floating on the upper layer of the melt is isolated from air, vacuum or atmosphere protection is not needed.

The present invention is described in detail as follows:

1、Fe₂O₃and Al powder as main reaction material for forming binding phase according to reaction formula The huge heat of reaction is released to melt the product. For adjusting the composition of the binder phase, it is possible to addAnd nickel powder, wherein the nickel powder accounts for 1-10% of the total mass of the reaction raw materials.

2. Titanium dioxide powder may be used in place of tungsten trioxide powder, mixed in the following reaction ratio:

(x ranges from 0.1 to 0.27)

3. A certain amount of WC or TiC powder, aluminium powder and iron oxide powder can be mixed according to the following reaction formula proportion to produce steel bonded hard alloy

(x is in the range of 0.5 to 2.45)

Or (x ranges from 0.1 to 2.36)

4. Putting the mixed powder into a graphite reactor, compacting, wherein the charging density is 0.5-2 g/cm³Igniting with tungsten wire, reacting to the bottom of the container, making liquid metal liquid flow out from the lower outlet, pouring into the cavity made of high temperature resistant material, cooling to obtain the steel bond hard alloy product.

The invention has the advantages that: simple process, simple equipment, energy saving and compact steel bonded hard alloy product.

Drawings

FIG. 1 is a schematic diagram of the reaction process of the present invention. Wherein, the graphite reactor 1, the ceramic layer 2 floating upwards in the reaction process, the liquid iron 3 containing hard phase separated in the reaction process, the molten pool 4 in reaction, the unreacted reaction raw material 5, the lower outlet 6 of the graphite container and the cavity 7 for casting.

Detailed Description

Example 1: 108g of aluminum powder, 160g of iron oxide powder, 10g of nickel powder, 232g of tungsten trioxide powder and 12g of graphite powder, uniformly mixing, filling into a graphite cylindrical container with the diameter of 10cm and the height of 10cm, and manually compacting. The bottom of the graphite is opened so that the liquid molten mass can flow out, and a high-temperature resistant cavity is placed below the opening. The tungsten wire is used for ignition, and after the reaction is finished, compact WC series steel-bonded hard alloy can be obtained in the cavity.

Example 2:

54g of aluminum powder, 160g of iron oxide powder and 50g of titanium carbide powder are used as a hard phase system. The rest of the steps are the same as the example 1, and the compact TiC steel-bonded hard alloy can be obtained.

Claims

1. A preparation method of steel bonded hard alloy is characterized by comprising the following steps: mixing iron oxide powder, aluminum powder, tungsten trioxide powder and graphite powder And (2) mixing the reaction formula, wherein the range of x is 0.5-3, igniting a tungsten filament to react, discharging huge heat after the reaction, generating aluminum oxide, wherein iron is in a molten state, tungsten and carbon are dissolved in liquid iron, the aluminum oxide is separated from the liquid iron under the action of gravity, the aluminum oxide floats on the upper surface of the iron, the tungsten and the carbon are combined with each other along with the reduction of temperature to generate tungsten carbide, a large amount of tungsten carbide is separated out in iron liquid, and removing an oxide slag layer on the surface after cooling to obtain the steel bonded hard alloy.

2. The method of claim 1, wherein: the specific process steps are as follows: fe₂O₃And Al powder as a reaction material for forming a binder phase according to the reaction formula The huge heat released by the reaction melts the product, and nickel powder is added for adjusting the binder phase components, wherein the nickel powder accounts for 1-10% of the total mass of the reaction raw materials; putting the mixed powder into a graphite reactor, compacting, wherein the charging density is 0.5-2 g/cm³Igniting with tungsten filament, making the liquid metal flow out from the outlet at the lower part when the reaction is carried out tothe bottom of the container, pouring the liquid metal into a cavity made of high-temperature resistant material, and cooling to obtain the steel bond hard alloy product.

3. The method of claim 1, wherein: titanium dioxide powder is used instead of tungsten trioxide powder Mixing the reaction formula in proportion, wherein x ranges from 0.1 to 0.27.

4. The method of claim 1, wherein: mixing a certain amount of WC powder with aluminum powder and iron oxide powder And mixing the reaction formula in proportion, wherein the range of x is 0.5-2.45, and generating the steel bonded hard alloy.

5. The method of claim 1, wherein: mixing a certain amount of TiC powder, aluminium powder and iron oxide powder And mixing the reaction formula in proportion, wherein x ranges from 0.1 to 2.36, and the steel bonded hard alloy is generated.