Exceed material of strong cutting tool -- diamond and cubic nitrogen change boron (one)

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Summary: Introduced to exceed material of strong cutting tool (diamond and cubic nitrogen change boron) process of phyletic, development, production method, function and applied limits, included a few cutting the test data of difficult treatment material. Keyword: Exceed hard data; Diamond; Cubic nitrogen changes boron; Cutting tool; Cutting function the main horniness composition of high-speed steel of material of 1 introductive and contemporary cutting tool, hard alloy, pottery and porcelain is carbide, nitride, oxide. For example, high-speed steel was to add alloy component (W, Mo) cementite; Hard alloy basically is carbide, nitride and carbolic nitride: Pottery and porcelain is oxide and nitride. The hardness of these compound is highest amount to 3000HV, add felt substance its are overall hardness is under 2000HV. To the treatment of modern project material, below certain circumstance, the hardness of afore-mentioned cutting tool material already not apply is used, exceed material of strong cutting tool then emerge as the times require, of 20 centuries hind there was greater progress in 40 years. The chemical part that exceeds hard data and the rule that its form hardness and material of other cutting tool are different, cubic nitrogen changes the boride of boracic dispute metal, crystal structure is face heart cube; And diamond is changed by carbolic element and become, its crystal structure and cubic nitrogen change boracic likeness. Their hardness greatly prep above is other material. Before thousands of years, the mankind has discovered and use natural diamond; And the production of making synthetic diamond and application are the thing in a century. Nitrogen changes boron is artifical. In 20 centuries later period, making synthetic diamond and cubic nitrogen change the development that boron exceeded hard data two kinds to get a flight. Making synthetic diamond is in more before high temperature, high pressure (hot pressing law) form below the condition, call PCD, appeared again later other production method. The research of PCD making synthetic diamond only then 1940, the United States proclaimed formally 1954 development of this kind of diamond is successful, began industrial production 1957. Sweden succeeds at proclaiming 1953, began industrial production 1962. To 1969, crop of whole world making synthetic diamond is 40 million carat (Carat) ; Natural at that time diamond produces per year a quantity to be 44 million carat. Chinese declare PCD made a success 1963. 1996, crop of Chinese making synthetic diamond is amounted to 2.

400 million carat, export 6 ～ 8.

Carat of 5 ten million. 90 time end, china produces per year a quantity to amount to 500 million carat, occupy whole world first place. The biggest foreign country company produces per year making synthetic diamond to also amount to above of 100 million carat in recent years. 1957, cubic nitrogen of CBN(of extrude of American GE company changes boron) single crystal pink, at the beginning of 70 time, make PCBN cutting tool of Cheng Jujing. 1972, russia also makes PCBN cutting tool. 1966, china develops CBN of successful single crystal. Later, make PCBN. In recent years, with deposit of chemical gas phase (CVD) legal system becomes making synthetic diamond. 2 exceed the sort of material of strong cutting tool to exceed material of strong cutting tool, especially diamond, its sort is more. Cubic nitrogen changes boron to CBN sheet tastes pink, use at making to grind; Still PCBN gets together chip and PCBN get together brilliant is compound piece, use at making tool of cutting tool etc. Cubic nitrogen changes boron is artifical. Diamond divides natural diamond (ND) and making synthetic diamond. Making synthetic diamond has white of PCD single crystal, use at making to grind; Bead of PCD single crystal, can make cutting tool; PCD gets together chip Ji Jujing is compound piece, use at making tool of cutting tool etc; CVD diamond film reachs thick film, can use at making cutting tool, tool, can regard high-tech of optical, electron as raw material. The production method that 3 exceed the production method man-made of material of strong cutting tool to exceed material of strong cutting tool is very much, here basically introduces hot pressing law and standard of gas phase deposit. The equipment that hot pressing legal system makes diamond and cubic nitrogen change boracic place to use is the hydraulic press of 6 tops or two sides top. Suppress single crystal exceeds hard data. In needing the housing pyrophyllite of raw material park. The raw material of pink of suppress PCD single crystal is black lead piece, black lead piece with activator Ni-Mn piece in cascade park housing; Suppress PCD gets together the raw material of chip is pink of PCD single crystal, join bond Ni, Si, Co to wait; The raw material of pink of suppress CBN single crystal changes boron for 6 nitrogen (HBN) pink; Suppress PCBN gets together the raw material of chip is pink of CBN single crystal, need to part at the same time buy person activator and bond. Sketch map of hot pressing craft sees a picture 1, graph 2. Its pressure, temperature and pressurization time all rank pursues medium. The pressure in pressurization process and step up, press eventually differ somewhat, the pressure in pyrophyllite housing and the pressure of ministry carrying hammer on the head are different also, graph 1, the pressure that the pressure that the graph shows 2 times is ministry of hammer pointing to a top. Temperature is antrum lukewarm. Time is to heat time, heat preservation time and drop in temperature the summation of the process such as time, to all sorts of press, these parameter will differ somewhat, the data that the article gives out is only probably number. Legal system of similar hot pressing builds PCD, still have " explosive law " , dynamite explosion is used to generate high temperature maximum pressure in container, and make diamond of black lead translate into. The craft of explosive law and product quality all are controlled not easily, reason is used formally rarely. CVD law is law of deposit of a kind of gas phase. Belong to principle of this kind of job the method of deposit on blame diamond base diamond is very much, be like " law of heater law CVD " , " the electron strengthens CVD law " , " microwave PCVD law " , " law of radio frequency PCVD " , " dc PCVD law " , " law of dc arc PCVD " , " law of CVD of dc plasma eject " . "Heater CVD law " most commonly used. Graph 3 grow for thick film of heater CVD diamond sketch map of deposit technology principle. Raw material is alcohol (alcohol) , hydric with methane, heater is Ta silk or W silk. Heat the heater of 2500 ℃ high temperature reachs 2000 ～ to be mixed in heater the plasma that voltage brings to bear on between matrix and forms, make hydrogenous element and dissociation of element of the gas that contain carbon, form atomic condition hydrogen and the carbon that can form SP3 to bolt hydrogenous radical is round. This radical group falls to experience adsorptive chemical process in the matrix surface of proper temperature in the effect that has atomic hydrogen, go hydrogen and the carbolic structure that forms diamond. The temperature that controls heater and bring to bear on voltage and current density, especially aeriform composition, grow the pressure of container and matrix temperature, the rate that controls film effectively to grow namely and the quality that become film. In matrix (underlay) go up after thick film, need to make film and matrix detached, and what cut becomes definite figure is small, fashion solder of small drill rod compound razor blade or cutting tool on hard alloy again, if pursue,4 are shown. If make cutting tool of CVD filmy diamond, be in cutting tool is direct deposit diamond is filmy can, film is deep control for 10 μ M only. And the ply of thick film can be amounted to 0.

5 ～ 0.

6mm above. 4 exceed the function of material of strong cutting tool to exceed hard data to have superior mechanical performance, physics function and other property, have some of property among them very agree with cutting tool. 4.

1 have very tall hardness the hardness of natural diamond amounts to 10000HV; The hardness of CBN amounts to 7500HV. Compare with appearance of other good material, siC hardness is 3000 ～ 3500HV, a12O3 is 2700HV, tiC is 2900 ～ 3200HV, WC is 2000HV, si3N4 is 2700 ～ 3200HV; Regard cutting tool material as used hard metal, its hardness is 1100 ～ 1800HV only. 4.

2 have very good thermal conductivity person like that does the thermal conductance of diamond amount to 2000W? M-1? K-1, does the thermal conductance of CBN amount to 1300W? M-1? K-1. The thermal conductivity of red copper is very good, is its thermal conductance 393W only? M-1? K-1; Is aluminium 226W? M-1? K-1, the thermal conductance of reason diamond and CBN is red copper respectively 5 times with 3.

5 times, be aluminium 8 times with 5 times. Is the thermal conductance of hard alloy 35 ～ 75W only? M-1? K-1. 4.

The 3 Yang model amounts that have very high Yang standard to measure natural diamond amount to 1000GPa, the Yang model quantity of CBN is in 720GPa. And the Yang model quantity of SiC, Al2O3, WC, TiC is respectively only 390, 350, 650, 330GPa. Yang model quantity of material is rigid greatly good. 4.

4 have very small heat to expand the linear expansion coefficient of natural diamond is 1 × 10-6/K, the linear expansion coefficient of CBN is (2.

1 ～ 2.

3) × 10-6/K. And the linear expansion coefficient of hard alloy is (10-6/K of × of 5 ～ 7) . 4.

5 have lesser density the density of natural diamond is 3.

52g/cm3, the density of CBN is 3.

48g/cm3. The density with Al2O3, Si3N4 is adjacent. 4.

6 have rupture inferiorly tenacity is natural of diamond rupture tenacity is 3.

4MPa? M0.

5, CBN is close to to it. Of material of cutting tool of pottery and porcelain rupture tenacity is to belong to in all sorts of cutting tool material inferior person, can you still amount to 7 ～ 9MPa like that? M0.

5. Reason diamond and CBN sex are fragile, it is its weakness. 4.

Thermal stability of 7 chemistry CBN is good, 1500 ℃ of 1300 ～ are amounted to to be not decomposed in atmosphere. Right element of iron a group of things with common features shows laziness; Do not suffer ooze corrode in acid, in alkaline in dip corrode suffers namely when about 300 ℃ ; The water vapour with overheat also can act well. Diamond issues chemistry stability in normal temperature; In oxygen about 660 ℃ begin graphitization, element of iron a group of things with common features especially iron element can be urged into graphitization; In acerbity, alkaline in do not suffer dip corrode. 4.

The does not contain impurity diamond with 8 electricity pure property is dielectric, is rate of the resistor below room temperature in 1016 Ω ? Cm above. Have mix into person only after other element, just show semiconductor character. Compare with the semiconductor material phase such as Si, Ce, As, diamond has very broad forbidden band, small dielectric constant, carry electronic mobility high, big electrical shock wears intensity, showing diamond is the high temperature of broad forbidden band with a kind of good performance (> 500 ℃ ) semiconductor material. Natural diamond does not have magnetism; In making synthetic diamond if contain the catalyst impurity such as Ni, Co, Fe, have magnetism, foreign matter is more, magnetism is stronger. 4.

Diamond of 9 optical property has very high refractive index and strong astigmatism sex, still have admirable pervious to light function, can pass through very broad wave band. Certain diamond is in till violet outskirt, visible area is far the greater part wave band of infra-red area (O.

22 ～ 2.

5 μ M) is transparent. Above exceeds the exceedingly good or excellent performance that hard data place has and property, decided they are having wide use. With natural diamond (ND) photograph is compared, man-made gets together brilliant diamond (quantity of model of the hardness of PCD) , Yang and thermal conductance are a bit low, rupture tenacity, heat expands rate is tallish. All sorts of function of man-made CVD diamond upright between ND and PCD, more adjacent at natural diamond. For example, the hardness of natural diamond amounts to 10000HV, PCD is 8000HV about, CVD diamond can amount to 9000HV. 5 exceed the nitrogen of applied limits cubic metre of material of strong cutting tool to change boron to have stability of tall hardness, high fever, right element of iron a group of things with common features shows laziness, reason suits to make cutting most the cutting tool of following material: Cutting hard steel of all sorts of temper by dipping in water, include steel of steel of carbolic element tool, alloy tool steel, high-speed steel, bearing, mould steel to wait; Cutting all sorts of iron base, nickel radical, cobalt radical and other thermal spraying (solder) spare parts. Diamond has taller hardness etc to actor or actress different function is used, the cutting tool that it makes, applied range is more wide, can machine all sorts of difficult treatment material, blame treatment material; To nonferrous metal, basically reach its alloy to copper, aluminium, undertake cutting is machined exceeding nicety; Because of diamond cutting tool, especially natural diamond cutting tool, its cutting blade can be ground very tartly, the blunt round radius of class of rice of OK and abrade cashier; Cutting pure tungsten, pure molybdenum; Glass of cutting project pottery and porcelain, hard alloy, industry; Cutting black lead, all sorts of plastic; Cutting all sorts of composite material, include metallic radical and metalloid base, fiber is strengthened and grain strengthens; With tools of all sorts of medical apparatus and instruments that use at place of dentistry, orthopaedics; Use at all sorts of lumber to machine cutting tool and tool of stone material treatment; ... diamond and cubic nitrogen change pink of boracic single crystal to be used at making abrasive in great quantities, grind, grind cream, emery cloth, sand paper. Diamond still is used at making to pull filar model, emery wheel to amend in great quantities implement with branch of mine of oil, land drill broach. Still use at all sorts of wear-resisting. Much can use the difficult treatment data of cutting of diamond cutting tool, wait like hard alloy, pottery and porcelain, glass, composite material, cubic nitrogen changes boracic cutting tool to also can be competent, but the service life that general and cubic nitrogen spends boracic cutting tool under diamond cutting tool. And diamond cutting tool cannot machine iron base material to expect. CNC Milling CNC Machining