A kind of preparation method of polycrystalline cubic boron nitride compound sheets
Technical field
The invention belongs to cutter material and manufacture field, the preparation method of high-quality polycrystalline cubic boron nitride (PcBN) composite sheet that a kind of cubic boron nitride content is controlled specifically, stability is high.
Background technology
Cubic boron nitride (cBN) is another the novel new and high technology superhard material occurred after diamond comes out.Its hardness is only second to diamond, but heat endurance is far above diamond, and to Ferrious material, unit have larger chemical stability.The grinding performance of CBN is very excellent, can not only be competent at the processing of difficult grind material, boost productivity, and effectively can also improve the grinding quality of workpiece.The use of cubic boron nitride is contributed greatly one of intermetallic composite coating, causes grinding generation revolutionary variation, is the second leap of grinding technique.
Modern mechanical process technology is just towards high accuracy, high efficiency, flexibility and automation direction develop rapidly, new technique equipment and the very excellent new material application of Digit Control Machine Tool, machining center and performance increasingly extensive, thus more and more higher to the requirement of cutter.As a kind of important application material of cubic boron nitride tool, polycrystalline cubic boron nitride (PcBN) cutter has fully demonstrated the requirement of modern manufacturing industry to material with its superior performance.PcBN cutter is particularly suitable for the hard turning of various ferrous metal, realizes with car generation mill.Not only improve and draw working (machining) efficiency, and considerably reduce processing cost, the various hardened steel of main cutting, tool steel, mould steel, bearing steel (HRC45-70), chilled cast iron, rich chromium cast iron, Ni-based and cobalt base superalloy, various difficulty processing grey cast-iron, other difficult processing black material etc.Because cubic boron nitride hardness is far above pottery and carbide alloy, the cutter life of preparation is 3-5 times of sintex, and the 5-15 of hard alloy cutter doubly.
PcBN composite sheet, at HTHP (4.8 ~ 5.2GPa, 1400 ~ 1550 DEG C) will independently rely on sintering bonding by cubic boron nitride powder particle under condition, whole cubic boron nitride powder layer is made to be sintered into the slug type cBN glomerocryst (thickness 0.5-2.0mm) of high strength " concrete " structure, and with carbide by sintering process compound, shape all-in-one-piece composite.Due to PcBN material because manufacture method, composite pathway and sintering mechanism are different, its properties of product also will show obvious difference.Analyze more than combining from present application and find out, wear resistance ratio is no longer leading indicator, because several its wear resistance ratio of system compact product all can meet the demands, high temperature resistance to wears, therefore cementitiousness and this two indices of toughness rise to main positions.From this cermet auxiliary agent of this angle type PcBN composite sheet, there are greater advantages.At present, in the method preparing PcBN, what adopt is all the sintering method that cubic boron nitride mixes with adhesive powder, it is characterized in that the content proportioning of cubic boron nitride and binding agent is difficult to reach optimum usually, synthesis condition interval is narrower, can bring as uneven in sintering structure structure simultaneously, " bridge formation ", " reunion " phenomenon, product stablizes the problems such as poor repeatability, the serious performance affecting PcBN instrument.
Therefore, high efficiency, high stability, high accuracy can be realized, the process of preparing of long-life PcBN superhard material is an important development direction of superhard material manufacturing, the application of PcBN cutter product will be day by day universal, and the demand of cubic boron nitride tool will keep the speed increment of annual more than 10%.
Summary of the invention
The object of the present invention is to provide a kind of workable, the preparation method of polycrystalline cubic boron nitride (PcBN) composite sheet that product percent of pass is high, effectively can regulate the content proportioning of boron nitride and binding agent, improve cBN glomerocryst sintering structure structure and compactness, effectively can reduce the defects such as " reunion ", " bridge formation " phenomenon of powder compounding process introducing simultaneously, the PcBN composite sheet of preparation according to tool demands, can become the cutter of the different angles trade mark with welding production through laser cutting.
The object of the present invention is achieved like this, and the method comprises the following steps:
1., choose sheet metal and the hard alloy substrate in same piece footpath, micron order cubic boron nitride powder is as raw material;
2., by above-mentioned 1. in sheet metal, the micron order cubic boron nitride powder after hard alloy substrate and purification chosen put into molybdenum cup and assemble, assembling mode is followed successively by sheet metal from bottom to up, the micron order cubic boron nitride powder of purification, hard alloy substrate;
3., the molybdenum cup 2. assembled is completed the preparation of glomerocryst boron nitride compacts through pre-molding, vacuum preheating, pyrophyllite composite block assembling, high-pressure sinter program.
Described sheet metal is Ni
75mn
16co
9, Ti or Al, thickness 0.05-0.2mm; Hard alloy substrate model selects YG8-YG13, thickness>=2mm; Micron order cubic boron nitride powder particle diameter is>=3 μm.
The thickness of the cubic boron nitride powder layer after described pre-molding is 1-2mm.
The assembling of described pre-molding, vacuum preheating, pyrophyllite composite block cavity, high pressure sintering processes are through 40MPa pre-molding by the molybdenum cup 2. assembled, put into the graphite heating pipe box part with salt pipe after vacuum 700 DEG C of heat treatment 1h, finally all parts are put in the lump pyrophyllite composite block assembling.Adopt " heater-type " mode of heating, cubic hinge press carries out HP-HT synthesize, and the synthesis condition of composite sheet is 4.8 ~ 5.2GPa, 1400 ~ 1550 DEG C, and the sintered heat insulating time is 3-10min.
Beneficial effect of the present invention is as follows:
1, the present invention adopts the infiltrating method of sheet metal can regulate the proportioning of cBN and binding agent in cBN glomerocryst layer, sintering structure dense uniform, synthesizes reproducible, decreases powder compounding process, workable.
2, sintering method of the present invention sweeps more formula melting infiltration sintering by sheet metal and hard alloy substrate, cBN glomerocryst layer and hard alloy substrate interface bond strength high.
3, due to interactive infiltration technique that preparation PcBN method of the present invention is by sheet metal and hard alloy substrate, its auxiliary agent can effectively infiltration to cubic boron nitride powder layer and hard alloy substrate, the sintering phases such as cubic boron nitride, Alloy solid solution, cermet are formed in cBN glomerocryst layer, its tissue of sintered body even structure is fine and close, and form the compound of high strength with hard alloy substrate, improve matrix toughness simultaneously.The method strong operability, can reduce the pollution that powder compounding process is introduced, the PcBN product stability of synthesis is high, is applicable to the Precision Machining field of the materials such as chilled cast iron, heat-resisting alloy and hardened steel.
Accompanying drawing explanation
Fig. 1 is raw material and the molybdenum cup assembly drawing of polycrystalline cubic boron nitride compound sheets of the present invention;
Fig. 2 is the pyrophyllite composite block cavity assembling sectional view in present invention process.
Detailed description of the invention
Label in Fig. 1: sheet metal 1, cubic boron nitride powder 2, hard alloy substrate 3, molybdenum cup 4;
Label in Fig. 2: pyrophyllite composite block 5, salt pipe 6, heated graphite pipe 7, raw material and molybdenum cup assembly 8, conductive steel cap 9, conductive metal sheet 10, insulation graphite flake 11, salt sheet 12.
Embodiment 1
As shown in accompanying drawing 1,2: the Ni choosing thick 0.2mm diameter 14.7mm
75mn
16co
9metal alloy film, particle diameter 3-5 μm, the cBN powder of quality 0.65g, with sheet metal same piece footpath, the YG8 hard alloy substrate of thickness 3mm is as raw material, according to sheet metal 1, cubic boron nitride powder 2 and hard alloy substrate 3 order from bottom to up put into the molybdenum cup 4 of internal diameter 14.8mm through 40MPa pre-molding, heated graphite pipe 7 external member with salt pipe 6 is put into after 700 DEG C, vacuum purification heat treatment 1h, finally put into pyrophyllite composite block 5 in the lump by the top raw material of two panels and molybdenum cup assembly 8 and parts 9-12, pyrophyllite composite block 5 is of a size of 37.5mm × 37.5mm × 37.5mm, synthetic cavity diameter is 23mm, graphite-pipe 7 internal diameter is 18mm, high 26mm.PcBN composite sheet carries out HP-HT synthesize on cubic hinge press, and synthesis condition is 5GPa, 1450 DEG C, cools to room temperature slowly after sintered heat insulating time 6min, obtains the PcBN composite sheet of Φ 14mm × 5mm after release.
Embodiment 2
As accompanying drawing 1, shown in 2: the Ti sheet choosing thick 0.1mm diameter 14.7mm, the cBN powder of particle diameter 3-5 μm quality 0.65g, with sheet metal same piece footpath, the YG8 hard alloy substrate of thickness 3mm is as raw material, the molybdenum cup 4 of internal diameter 14.8mm is put into according to sheet metal 1 cubic boron nitride powder 2 and hard alloy substrate 3 order from bottom to up, through 40MPa pre-molding, heated graphite pipe 7 external member with salt pipe 6 is put into after 700 DEG C, vacuum purification heat treatment 1h, finally put into pyrophyllite composite block 5 in the lump by the top raw material of two panels and molybdenum cup assembly 8 and parts 9-12, pyrophyllite composite block 5 is of a size of 37.5mm × 37.5mm × 37.5mm, synthetic cavity diameter is 23mm, graphite-pipe 7 internal diameter is 18mm, high 26mm.PcBN composite sheet carries out HP-HT synthesize on cubic hinge press, and synthesis condition is 5GPa, 1500 DEG C, cools to room temperature slowly after sintered heat insulating time 6min, obtains the PcBN composite sheet of Φ 14mm × 5mm after release.