CN100436065C - Method for treatment of binding agent for super hard abrasive tools - Google Patents

Abstract

A method for preparing ultra-hard grinding tool with metallic binder features that the mixed metallic powder is ball-ground in high-energy ball grinder to make the particles in a high-energy state, and in the following sinter procedure, the energy accumulated in metallic particles is released, so resulting in lower sinter temp and high sinter performance.

Description

A kind of processing method of superhard abrasive tool bond

technical field

The invention relates to a method for treating a bond in a metal bond superabrasive tool.

Background technique

Traditional metal-bonded superabrasives are uniformly mixed with various metal powders and superabrasives (such as diamond, cubic boron nitride, etc.) according to the calculation, then weighed, put into a mold, pressed, and sintered to become The metal bond-superabrasive complex combined with a metal bond and containing a certain proportion of superabrasives becomes the working part of the superabrasive tool. Because the quality of diamond and cubic boron nitride deteriorates seriously at high temperature, the sintering temperature is generally limited to below 900°C, and the commonly used temperature is between 750 and 850°C, and the holding time should be as short as possible.

In order to meet the requirements of the performance of superabrasives on the binder during the working process, the binder is generally composed of Cu, Co, Ni, Fe, W, WC, etc., but these metals have high melting points and are difficult to sinter below 900 ° C. Therefore, Generally, metals with low melting point such as Sn and Zn are added to improve sintering performance. The addition of low-melting point metals often reduces the mechanical properties of the sintered body after sintering, and the selectivity of mutual solubility is also strong, such as better compatibility with Cu, Co, Ni, etc., but poor compatibility with cheap Fe. The fundamental reason is that this temperature range cannot achieve effective alloying between the metal powder particles in the components, and thus cannot form good solid-state sintering.

For this reason, professional and technical personnel have carried out relevant research, and improved this problem through the method of pre-alloying. There are two types of pre-alloying currently used: one is through metallurgical smelting-injection atomization to make powder, so that each powder particle has the same composition to make alloy powder. The disadvantage of this method is that the powder particles are spherical during the injection process, and the sintering activity is poor; the other method is to use chemical co-deposition, through a variety of materials (generally 2 to 3 kinds) as the anode electrolysis, the fine powder is combined in a certain proportion. Deposition, forming a finer mixture, partly forming chemical mutual solubility, and after post-processing, a certain degree of alloying is achieved. The disadvantage is that due to the problem of electrolysis, the composition of the alloy is limited, it is difficult to achieve alloying of ternary or more, and the later treatment is very troublesome; the above two methods have their own shortcomings, but the common disadvantage is that they must be produced in a professional manufacturer of metal powder. For superhard abrasive manufacturers, they cannot flexibly prepare components by themselves.

Mechanical alloying (Mechanical Alloying,) as a new method of preparing new materials, can be used to manufacture amorphous phase and nano phase, can break the restriction of the phase diagram, and manufacture multi-element supersaturated solid solution alloys. Technologists have used it to successfully prepare various new alloys such as amorphous, nanocrystalline, intermetallic compounds, metal matrix composites, dispersion-strengthened materials, high-temperature materials, magnetic materials, and supersaturated solid solutions. This kind of alloying is different from the traditional hydrometallurgical alloying. The mechanical alloying process is to mechanically mix the material powders that need to be alloyed according to a certain ratio with high energy density, and run for a long time in high-energy ball mills and other equipment to convert the mechanical energy. At the same time, under the impact of multiple large energy of the ball milling medium, the powder undergoes multiple forces of shearing, friction and compression to form repeated extrusion, cold welding and crushing, and the mutual diffusion or The process of solid-state reaction to form dispersed ultra-fine particle alloy powder. In this process, through a large number of plastic deformation, crushing, and welding, mechanical energy is converted into various unbalanced conditions for storage, such as the surface energy of fine particle size , the interface energy of grain size refinement, the potential energy generated by a large number of defects such as dislocations, and the potential energy generated by atoms deviating from the equilibrium point when the lattice constant becomes larger; this method can make many elements that cannot be alloyed by other methods Form a solid solution, Cu-Fe alloy is a typical representative.

Gilman and Benjamin divided the ball milling process of mechanical alloying into the following four stages:

1. The powder particles in the initial stage are layered composites of the original components. In the composite particle, the original components are recognizable, the composition varies greatly from particle to particle, and the internal composition of the particle is very uneven.

2. In the middle stage, the particles become spiral layers, and the solute elements begin to dissolve. Due to the kinetic energy of the absorbing balls, the temperature of the powder rises, severe cold deformation causes high-density lattice defects, strengthens the pipe diffusion with low activation energy, and the intimate mixing of components reduces the diffusion distance. These all promote the formation of solid solutions throughout the particle range. At this point precipitation within the particles can occur and a metastable phase can form. The particles become more dispersed and the distribution gradually becomes uniform.

3. The final stage layer becomes finer and more convoluted, and the average composition range of the powder mixture of individual particles narrows. The distance between layers becomes smaller. Particles still contain regions with a high concentration of a component and residual intermetallic compounds. The precipitation of the equilibrium phase becomes possible, and the microhardness of the particles reaches the saturation value. In the early stage of the MA process, the hardness increases roughly linearly with the progress of MA. After reaching saturation, the balance between work softening and further work hardening keeps the hardness at a certain level.

4. The powder particles in the finished stage have serious cold deformation, and the layered structure is not easy to distinguish under the microscope; the composition of the powder particles is now consistent with the average composition of the raw material powder mixture. After reaching this level, further ball milling has no substantial effect on improving the distribution of dispersed particles. Any impurities that are unintentionally introduced into the system are also refined during the ball milling process, and are evenly distributed without forming large inclusions. Severely cold deformed structures form ultrafine grains.

Through the above process description and literature search on mechanical alloying, it is believed that the mechanical alloying method is mainly used to prepare amorphous, nanocrystalline, intermetallic compounds, metal matrix composites, dispersion strengthened materials, high temperature materials, magnetic materials, supersaturated solid solutions A variety of new alloys, such as energy storage and surface activation in the process of mechanical alloying, have not been reported in the manufacture of metal bond superhard abrasive tools. The present invention obtains through experiments that after a certain period of time (about completing the above-mentioned intermediate stage), the energy storage in the powder reaches the highest value, as shown in FIG. 1 .

It can be seen from Figure 1 that after mechanical alloying for 30 hours, the energy release of Cu-Fe powder reaches the maximum value during the heating process. If the time is too long, the energy storage will be reduced, and the beneficial effect on solid-state sintering will be reduced. It can also be seen from Figure 1 that after mechanical alloying treatment at different times, the melting temperature of the powder remains unchanged, indicating that the stored energy formed by mechanical alloying before the powder components are melted is completely released during the heating process. This release process reaches the highest density at a temperature of 500-800°C, which is the common temperature range for sintering superhard abrasive tools. The energy release process eliminates the imbalance in the material structure, promotes the diffusion of atoms, and the fresh and activated surface is conducive to the transfer of substances between the solid-state interfaces, thereby achieving the purpose of good sintering.

The present invention is different from general mechanical alloying, and the mechanical alloying method is mainly used for preparing amorphous, nanocrystalline, intermetallic compounds, metal matrix composite materials, dispersion strengthened materials, high temperature materials, magnetic materials, supersaturated solid solutions, etc. new type of alloy, and the present invention mainly uses the method of mechanical alloying to make the powder particles achieve higher energy storage in the process of mechanical alloying, so as to strengthen the solid-state sintering degree of the binder in the metal bond superabrasive tool, Lowering the sintering temperature is a treatment method for improving the bonding agent of metal bonded superhard abrasive tools. Through a stage of treatment in the mechanical alloying process, the processed bonding agent powder can be easily sintered at a lower temperature. And improve the quality of solid-state sintering; another difference of the present invention is that only the method of mechanical alloying is used to achieve higher energy storage of the processed powder and to form a fresh, activated particle surface, regardless of whether it is completely alloyed or whether it has reached mechanical alloying other effects.

Compared with other pre-alloying methods used in the manufacture of metal-bonded superhard abrasive tools, mechanical alloying equipment is relatively common and can be bought on the market, which is very suitable for superhard abrasive tool manufacturers to purchase and use. Manufacturers of superhard abrasive tools can more flexibly prepare powder components according to requirements, without the need to purchase from professional manufacturers.

Contents of the invention

The purpose of the present invention is to provide a processing method of superhard abrasive tool bond, which adopts the method of mechanical alloying, and carries out mechanical alloying treatment to the metal powder of the bond of metal bond abrasive tool to achieve higher The degree of energy storage is enough, and it is not necessary to completely realize alloying, so that the binder metal powder can reduce the sintering temperature and improve the sintering quality.

The present invention utilizes mechanical alloying method to process the bonding agent metal powder process of metal bonding agent superhard abrasive tool as follows:

1. Mix the weighed binder metal powder with a certain amount of steel balls, ball: material = 5 ~ 15: 1, and put it into a steel ball mill tank.

2. Generally, a planetary ball mill or a self-designed high-energy ball mill is used. The present invention adopts a model XM-4×05 planetary ball mill produced in Nanjing.

3. A certain amount of process control agent is added to the binder metal powder in the ball mill tank at the same time. The process control agent is methanol, ethanol, carbon tetrachloride or methanol.

4. During the mechanical alloying process, the ball mill tank is filled with an inert gas, usually argon. Stop the machine after 20 to 30 hours of mechanical alloying, take out the metal powder after mechanical alloying, and then mix it with diamond, cubic boron nitride and other abrasives for sintering.

The advantages of the present invention are: the ability of the binder to be sintered is improved, good sintering can be formed at low temperature, the strength of the sintered product is improved, and the hardness and strength of the Cu-Fe powder after sintering at 800°C under the same conditions are respectively increased. 125% and 117% (as shown in Figure 2), can be easily applied in general product manufacturers.

Description of drawings

Fig. 1 is Cu50-Fe50DSC curve of different mechanical alloying time;

Fig. 2 is the relationship curve between different mechanical alloying time and sintered body hardness and flexural strength;

Figure 3 is the metallographic structure obtained by sintering at 800°C for 5 minutes after different mechanical alloying treatments. a mechanical alloying 0h; b mechanical alloying 10h; c mechanical alloying 30h.

Detailed ways

Example 1

用于切割混凝土的圆锯片，切割旧高速公路1200M。Preliminarily mix the metal powder with a mass ratio (wt%) of Cu 50%, Fe 50%, and an average particle size of 32-40 μm, put it into a steel ball mill jar, and add GCr15 with a diameter of 14mm according to 10 times the mass of the metal powder. steel ball, and drop into the metal powder mass 2% methanol as a process control agent. After sealing, open the vacuum valve to evacuate, and then inject argon. Place the ball mill jar on the XM-4×05 planetary ball mill, adjust the rotation speed to 200r/min, and the reverse frequency to 40Hz. After continuous mechanical alloying for 30 hours, the ball mill jar was removed and left for 5 hours, and then the mechanically alloyed metal powder was taken out. The processed metal powder is not subjected to any other treatment. After calculation, it is directly weighed and added to a graphite mold with a cavity of 4×7×40mm for the manufacture of small saw blade heads, and placed in a RYJ-98A type thermal On a pressure sintering machine, hold at 20MPa, 800°C for 4 minutes to obtain a completely different sintered structure, as shown in Figure 3. Its performance is shown in Figure 2. The above metal powder is manufactured according to the hot pressing and sintering manufacturing process of diamond saw blades, and is made into

Circular saw blade for cutting concrete, cutting old highway 1200M.

Example 2

Preliminarily mix the prepared metal powder according to the table below, put it into a steel ball mill tank, add GCr15 steel balls with a diameter of 14mm according to 10 times the weight of the metal powder, and drop methanol with a weight of 2% of the metal powder for the process control agent.

raw material Cu Fe Ni Zn Sn SiC Diamond Wt% 40.0 20.0 7.5 6.5 4.4 7.0 14.6

After sealing, open the vacuum valve to evacuate, and then inject argon. Place the ball mill jar on the XM-4×05 planetary ball mill, adjust the rotation speed to 200r/min, and the reverse frequency to 40Hz. After continuous mechanical alloying for 30 hours, the ball mill jar was removed and left for 5 hours, and then the mechanically alloyed powder was taken out. The treated powder is not subjected to other treatment, weighed after calculation, added to the graphite mold used to manufacture ultra-thin small saw blades with a thickness of 0.2mm, and placed on the RYJ-98A hot-press sintering machine. 20MPa, 780°C, hold for 3 minutes, made Circular saw blades for cutting monocrystalline silicon, cutting monocrystalline silicon wafers with good results.

Claims (5)

1. the processing method of a binding agent for super hard abrasive tools, it is characterized in that: the mechanical milling process by mechanical alloying makes metal-powder reach the middle high-energy storing state of process, reduces sintering temperature in the bond sintering process, improves sintering quality and alloying level with this; This method may further comprise the steps:

A. metal-powder that will mix in proportion and quality are packed in the ball grinder for its steel abrading-ball of 5～15 times, the adition process controlling agent, afterwards ball grinder is found time and charge into inert gas after seal;

B. the ball grinder that filling is finished places on the ball mill, rotates 10～30 hours under the condition of 200～400 rev/mins of rotating speeds, shuts down to take off ball grinder and seal and places 1～5 hour, with cooling combined metal-powder; Open ball grinder then, take out metal-powder and it is separated with the steel abrading-ball;

C. the metal-powder that above-mentioned high-energy ball milling is handled is suppressed and sintering by common super-hard abrasive tool manufacture method, and its sintering temperature reduces, or equal temperature obtains better sintering character.

2. the processing method of binding agent for super hard abrasive tools according to claim 1, it is characterized in that: described metal-powder is the binary or the multicomponent compound metal powder of Cu, Fe, Co, Ni, Sn, Zn, Al, Mn, Cr, W metallic element.

3. the processing method of binding agent for super hard abrasive tools according to claim 1 and 2, it is characterized in that: ball mill is in rotation direction of each cycle inner conversion in the rotation process, and the described cycle is 30～100 seconds.

4. the processing method of binding agent for super hard abrasive tools according to claim 1, it is characterized in that: described process control agent is methyl alcohol, ethanol, CCl ₄Or stearic acid, quantity is that per 100 gram metal-powders add 3～10 milliliters.

5. the processing method of binding agent for super hard abrasive tools according to claim 1, it is characterized in that: described inert gas is an argon gas.

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