JPS5887247A - Fine particle bonded hard carbide element - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a bundled carbide element, and more particularly to a bundle using nickel as a metal binder and containing a grain growth inhibitor to ensure a fine grain structure of the carbide. It concerns tungsten carbide elements. Examples of bound carbide elements include punches, dies, copper processing tools such as those forming rings, and other drawing elements used to form two-piece seamless cans. Copper machining tools must have high hardness and must be resistant to corrosion by synthetic lubricants.

The copper processing tools used to make two-piece seamless cans are:
Currently, cobalt is used as a metal binding agent,
Made from bonded tungsten carbide.

It is desirable to use synthetic lubricants to form two-piece seamless cans because of their cost and the ecological concerns associated with the treatment of lubricants as discussed above. However, bonded tungsten carbide cobalt tools are extremely abrasive because the bonded carbide does not resist corrosion from synthetic lubricants. Therefore, copper phase tools made from bonded tungsten carbide cobalt alloys have a very short lifespan due to relatively rapid wear. A short tool life cannot be tolerated in the can manufacturing industry. This is because the typical bell production line, which produces about 1,000 cans per minute, has to be interrupted to replace worn tools, and such production interruptions increase costs. It is.

Bonded tungsten carbide alloys are used in a variety of cutting, machining, and forming operations, and the basic alloy consists of tungsten carbide with cobalt, nickel, and/or iron metal bonding.

To suppress the growth of carbide particles during sintering, it is advisable to add small amounts of vanadium carbide to the basic tungsten carbide alloy. For example, U.S. Pat.
．． No. 165,822 teaches that 2 to 25 inches of nickel may be used as a metal binder in a tungsten carbide alloy that may also contain vanadium carbide. U.S. Patent No. 2,781. ?
No. 10 contains up to 12% nickel as a metal binding agent,
A bonded tungsten carbide alloy containing secondary carbide is presented. This US patent states that the particle size of tungsten carbide in known alloys is 0.5
Although a typical size of 8 to 8 microns is indicated, the aim of this patent is a cohesive carbide composition containing large particles of 25 to 250 microns. Furthermore, U.S. Patent Re, No. 22,073, 8-
An alloy containing 22% nickel with the balance consisting of tungsten carbide and some vanadium carbide has been disclosed.

Therefore, the bundled tungsten carbide element of the present invention contains 88% tungsten carbide and 1% tungsten carbide by weight.
It consists of 2% nickel and about 0.1% vanadium carbide, each carbide in a particulate structure. The fine particles mentioned here are all carbide particles.
It means having a size of 1 micron or less. The tungsten carbide element has a high resistance to corrosion by synthetic lubricants, has no microporosity, has high wear resistance, and has a hard surface, so it can be used as a copper tool material to form a two-piece seamless can. It is particularly suitable as

The above bound tungsten carbide has a weight ratio of 8
It consists of 8 inches of tungsten carbide, 12 inches of nickel, and about 0.1% vanadium carbide. Tungsten carbide has a very fine grain size, with all grains being less than 1 micron. The fine grain size of tungsten carbide is produced by processing tungsten carbide powder in the manner described below and sintering compacted ingots from the powder under conditions that inhibit grain growth. Furthermore, the vanadium carbide included in the above composition acts as a particle growth inhibitor during sintering.

Bound particulate tungsten carbide having the composition described above has high hardness and excellent corrosion resistance, which is advantageous when synthetic lubricants are used between the forming tool and the metal being formed. This is important when a copper machining tool is constructed to form a two-piece seamless can. Particulate tungsten carbide having the above composition has significantly higher wear characteristics in the above environment than large particle tungsten carbide using cobalt as a metal binding agent. A secondary advantage of the above alloys is the lower cost of nickel than cobalt.

Next, two sets of experimental examples having the compositions shown below in terms of weight ratio were prepared.

Tungsten carbide 88 tin
12% vanadium carbide
0.1% carbon
The 0.08% tungsten carbide has a particle size below the Fischer mesh size, between 1.55 and 2.
．． 02 microns.

The material was ground in a friction mill containing hexane and 40 to 9 carbide spheres for 5 hours. The powder thus obtained was dried, mixed with 2% soybean and compressed into rods.

This bar was sintered in vacuum at 1400°C for 1 hour. The physical properties of the bundled sintered carbide rods are as follows.

1st group 2nd group Average hardness (RA) 88.4 88.
1 density C? /cr-) 14.80
14.85 Transverse fracture strength Cp8i) 81? ,0
00 300,000 Microporous Al or less, Al or less.

Slightly B, CB Slightly B, C21 20tsi shrinkage rate 17.8chi 17.8
Two molds for copper processing were also made from the above powder.

This die mold has a neutral pH value, S, H, Mack
PTL540, L, L, 112 CPTL540/H
It was tested by immersion in a water-soluble synthetic oil named zO=%). This die showed no evidence of any corrosion.

Next, an eighth set of samples having the following weight ratios were prepared and sintered according to the present invention.

Tungsten carbide 88 tin
12% vanadium carbide
0.2% carbon
The 0.02% tungsten carbide had a size of 1.63 microns, below the sieve size.

After the above material was ground in a friction mill for 5 hours and dried, it was mixed with 2% soybean and the sample was “;1Ot
It was compressed with a compressive force of si. The sample was de-sintered in a hydrogen atmosphere and sintered in vacuum at 1470° C. for 1 hour. The physical properties of the bound carbide samples are as follows.

Average hardness (RA) 89.5 Density (f/cc
, ) 14.46 Transverse fracture strength Cpsi)
404,000 microporous degree
Less than Al, slightly shrinkage at B20tsi
18.1% The microstructure of this carbide was microparticulate.

The bundled tungsten carno (id) according to the present invention is
Two bound tungsten carbides using 15% Cono(rut) as the metal binding agent were compared to two bonded tungsten carbides. One of the carbides using Cono(rut) as the metal binding agent was 1 chrome carbide.The eight carbides include the sample, S,
H, Mack PTL540, Z,, L, 112 (
At room temperature, the
A corrosion test was conducted for several days. No visible signs of corrosion were observed for the bound carbide containing nickel binder according to the present invention. After 40 hours of soaking,
Car-guido containing a cobalt binder exhibited high corrosion, as did car-guido containing a cobalt binder with the addition of chromium carbide. Indicated.

Therefore, it is believed that the combination of nickel binder and particulate carbide provides hardness comparable to cobalt grade, lower corrosion, and higher abrasion resistance.

The surface of the bundled tungsten force-bit copper machining tool used to form the two-piece seamless can is lapped with diamond paste to give a smooth finish. Therefore, the bound carbide must be free of microporosity, excess carbon phase, and carbon deficiency phase that are detrimental to the surface finish. The reason why nickel is used as a metal binding agent for tungsten carbide according to the present invention is as follows. That is, nickel dissolves less carbon than cobalt, and is an effective catalyst for decomposing paraffin sludge, which plays an important role as a compression binder and lubricant for bound carbide powder. . However, for bound carbides containing nickel binding agents, the processing conditions must be more strictly regulated than for those using cobalt as the binding agent.

The preparation of the carnoide powder having the composition according to the invention into elements is carried out by the following method: first, an ingot is hydraulically compressed from the lumber-free powder. Pre-sintering is carried out in a decarburizing atmosphere of dissociated ammonia having a dew point of better than 20° F. The top condition of 700° C. is then maintained for 2 hours.

The ingot is then gradually machined into a green part of the desired size and shape. This part is sintered until it reaches its highest point. The sintering furnace is evacuated and filled with hydrogen to a partial pressure of 380 mm of mercury. The temperature was raised to 600°C, the hydrogen was evacuated from the furnace, and then the temperature was raised to 1800°C under vacuum,
Pronokun is then added to the furnace to a partial pressure of 38011i. The carnoid charge is maintained for 30 minutes, after which the furnace is evacuated and maintained at a maximum temperature of 1450°G for 1 hour. The sintered part was cooled in vacuum and heated at 15,000 ps.
HIP at 1800°C for 1 hour in argon gas at
Inside, it is treated in thermal equilibrium to eliminate internal porosity.

If bonded carbide elements using nickel as the metal bonding agent and having a particle size of less than 1 micron are treated in the manner described above, they will have sufficient hardness and high resistance to corrosion by synthetic lubricants, and a copper phase A high wear resistance when used as a tool is achieved. It is believed that the corrosion and wear resistance of copper phase tools made from the bound carbides described above result from the synergistic effect of the nickel metal binding agent and the extremely fine particle size.

While the above are selected aspects of the invention, it is to be understood that the invention may be practiced within the scope of the claims.

Claims (1)

[Claims] 1. 88% tungsten carbide, 12% by weight
of nickel and about 0.01% vanadium carbide, the carbide having a maximum particle size of 1 micron or less, and a synthetic lubricant. 2. A bound rigid force-node element according to claim 1, wherein said element is a copper machining tool for use in making a two-piece seamless can. , the heat treatment of the element results in a tungsten carbide,
nickel and vanadium carbide ingots,
Pre-sintering in a decarburizing atmosphere at a maximum temperature of about 700°C for a maximum period of about 2 hours, followed by sintering at successively increasing temperatures to a maximum temperature of about 1450°C. A bound hard carbide element as claimed in claim 1 or 2, comprising the following: 4. When the sintering is carried out in a furnace filled with hydrogen at a partial pressure of 380 dragons of mercury and heated to 600 °C, the furnace is evacuated and the temperature is increased to 1800 °C, and then 380 °C is heated.
additionally charging the furnace with propane to a partial pressure of 1i+;
and maintain the additional charging state for 80 minutes and evacuate the furnace;
and increasing the temperature of the furnace to 1450° C. for one hour. 5. A bound hard carbide element according to claim 4, comprising gradually machining an initially sintered ingot to the size and shape of the element. 6. The element comprises oil-pressure shrinking of an ingot consisting of powders of tungsten carbide, nickel and vanadium carbide, and pre-sintering of the ingot in a decarburizing atmosphere at a temperature of about 700°C. sintering, gradually machining the pre-sintered ingot to the size and shape of the element, and increasing the temperature sequentially by 1, 4.
A bound hard carbide element according to claim 1 or 2, formed by sintering the ingot at elevated temperatures of up to 50°C.