CN109208443B - Polycrystalline diamond composite cutting tooth synthesis block and method for synthesizing polycrystalline diamond composite cutting tooth by using same - Google Patents

Polycrystalline diamond composite cutting tooth synthesis block and method for synthesizing polycrystalline diamond composite cutting tooth by using same Download PDF

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CN109208443B
CN109208443B CN201811004619.4A CN201811004619A CN109208443B CN 109208443 B CN109208443 B CN 109208443B CN 201811004619 A CN201811004619 A CN 201811004619A CN 109208443 B CN109208443 B CN 109208443B
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polycrystalline diamond
ring
layer
heating tube
pyrophyllite
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CN109208443A (en
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卢灿华
张涛
窦明
刘俊涛
宋子衡
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Zhongnan Diamond Co Ltd
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Zhongnan Diamond Co Ltd
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    • E—FIXED CONSTRUCTIONS
    • E01—CONSTRUCTION OF ROADS, RAILWAYS, OR BRIDGES
    • E01C—CONSTRUCTION OF, OR SURFACES FOR, ROADS, SPORTS GROUNDS, OR THE LIKE; MACHINES OR AUXILIARY TOOLS FOR CONSTRUCTION OR REPAIR
    • E01C23/00—Auxiliary devices or arrangements for constructing, repairing, reconditioning, or taking-up road or like surfaces
    • E01C23/06—Devices or arrangements for working the finished surface; Devices for repairing or reconditioning the surface of damaged paving; Recycling in place or on the road
    • E01C23/08—Devices or arrangements for working the finished surface; Devices for repairing or reconditioning the surface of damaged paving; Recycling in place or on the road for roughening or patterning; for removing the surface down to a predetermined depth high spots or material bonded to the surface, e.g. markings; for maintaining earth roads, clay courts or like surfaces by means of surface working tools, e.g. scarifiers, levelling blades
    • E01C23/085—Devices or arrangements for working the finished surface; Devices for repairing or reconditioning the surface of damaged paving; Recycling in place or on the road for roughening or patterning; for removing the surface down to a predetermined depth high spots or material bonded to the surface, e.g. markings; for maintaining earth roads, clay courts or like surfaces by means of surface working tools, e.g. scarifiers, levelling blades using power-driven tools, e.g. vibratory tools
    • E01C23/088—Rotary tools, e.g. milling drums
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F5/00—Manufacture of workpieces or articles from metallic powder characterised by the special shape of the product
    • B22F2005/001—Cutting tools, earth boring or grinding tool other than table ware

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  • Mechanical Engineering (AREA)
  • Mining & Mineral Resources (AREA)
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  • Manufacturing & Machinery (AREA)
  • Powder Metallurgy (AREA)
  • Earth Drilling (AREA)
  • Cutting Tools, Boring Holders, And Turrets (AREA)

Abstract

The invention discloses a polycrystalline diamond composite cutting tooth synthesis block and a method for synthesizing a polycrystalline diamond composite cutting tooth by using the same, wherein the polycrystalline diamond composite cutting tooth synthesis block comprises a synthesis cavity for sintering a polycrystalline diamond composite cutting tooth blank at high temperature and high pressure, an isolation layer, a heating layer, a heat insulation layer and a cylindrical shell are sequentially sleeved on the side wall of the synthesis cavity from inside to outside, a conductive layer and a conductive pressure transmission layer I are sequentially arranged at the top of the synthesis cavity from inside to outside, and a conductive pressure transmission layer II is arranged at the bottom of the synthesis cavity; be equipped with polycrystalline diamond compact blank and isolation cap in the synthetic intracavity, the layer that generates heat comprises heating tube I, connecting washer and heating tube II, heating tube II's external diameter is greater than heating tube I, heating tube II's external diameter is the same with connecting washer, the tube-shape shell is the pyrophyllite piece.

Description

Polycrystalline diamond composite cutting tooth synthesis block and method for synthesizing polycrystalline diamond composite cutting tooth by using same
Technical Field
The invention belongs to the technical field of manufacturing of superhard materials, and particularly relates to a polycrystalline diamond composite cutting pick synthesis block and a method for synthesizing a polycrystalline diamond composite cutting pick by using the same.
Background
The polycrystalline diamond composite cutting pick is characterized in that a high-temperature and high-pressure technology is adopted on a diamond synthesis press, diamonds are compounded on the surface of a hard alloy ball tooth, a diamond thin layer with good wear resistance is formed on the surface, and meanwhile, the hard alloy has good impact toughness by utilizing the good impact toughness of the hard alloy. The cutting tooth is used as a cutting tooth of a road milling machine (a heading machine), participates in the cutting of an asphalt concrete pavement, and plays an important role in the milling of the asphalt concrete pavement of the expressway and municipal maintenance operation.
At present, when the traditional synthetic block assembly structure is used for synthesizing the polycrystalline diamond composite cutting tooth, the problems of unstable quality and low performance of the synthesized polycrystalline diamond composite cutting tooth easily occur due to the large length-diameter ratio of the traditional synthetic block assembly structure. Therefore, the traditional composite block assembly structure cannot meet the requirement of synthesizing the polycrystalline diamond composite cutting pick with a larger long diameter.
Disclosure of Invention
The invention aims to provide a polycrystalline diamond composite cutting pick synthesis block and a method for synthesizing a polycrystalline diamond composite cutting pick by using the same.
Based on the purpose, the invention adopts the following technical scheme: a polycrystalline diamond composite cutting tooth synthesis block comprises a synthesis cavity for sintering a polycrystalline diamond composite cutting tooth blank at high temperature and high pressure, wherein an isolation layer, a heating layer, a heat insulation layer and a cylindrical shell are sequentially sleeved on the side wall of the synthesis cavity from inside to outside; the synthetic intracavity is equipped with polycrystalline diamond composite cutting tooth blank and isolation cap, the top at polycrystalline diamond composite cutting tooth blank is established to the isolation cap, the layer that generates heat comprises heating tube I, connecting washer and heating tube II, heating tube II's external diameter is greater than heating tube I, heating tube II's external diameter is the same with connecting washer, the tube-shape shell is the pyrophyllite piece.
Furthermore, the conducting layer is composed of a trapezoid conducting post, a heat preservation ring and a conducting piece, the thickness of the heat preservation ring is the same as the height of the trapezoid conducting post, the heat preservation ring is matched with the trapezoid conducting post, the heat preservation ring is sleeved outside the trapezoid conducting post, the top and the bottom of the heat preservation ring and the trapezoid conducting post which are sleeved together are respectively provided with an upper conducting piece and a lower conducting piece, the trapezoid conducting post is made of graphite or molybdenum, the heat preservation ring is made of dolomite, and the conducting piece is made of a graphite plate or a molybdenum plate.
Further, the conductive laminated layer I consists of a pyrophyllite ring I, a conductive steel ring I and a dolomite core I; conductive steel ring I cover is established outside dolomite core I, pyrophyllite ring I cover is established outside conductive steel ring I, conductive steel ring I's external diameter equals the external diameter of heat preservation ring, pyrophyllite ring I's external diameter equals the external diameter of heat preservation layer (promptly pyrophyllite ring I lid is established at the top of heat preservation).
Further, the conductive pressure transmission layer II consists of a pyrophyllite ring II, a conductive steel ring II and a dolomite core II; conductive steel ring II cover is established outside dolomite core II, pyrophyllite ring II cover is established outside conductive steel ring II, dolomite core II's external diameter equals the external diameter of isolation layer (dolomite core II fills up the bottom at the isolation layer promptly), conductive steel ring II's external diameter equals heating tube II's external diameter, pyrophyllite ring II's external diameter equals the external diameter of heat preservation (pyrophyllite ring II fills up the bottom at the heat preservation).
Further, the heating tube I and the heating tube II are made of graphite, iron-chromium-aluminum alloy, titanium or molybdenum, the connecting gasket is made of titanium, molybdenum, zirconium or tantalum, the isolation layer and the isolation cap are made of analytically pure sodium chloride, and the heat insulation layer is made of dolomite.
Further, the isolation layer is two-layer stair-shaped structure, and two-layer stair-shaped structure is last stair-shaped structure and lower ladder-shaped structure respectively, and heating tube I is located the lateral surface of last stair-shaped structure, and the connecting washer is located the shoulder of two-layer stair-shaped structure, and heating tube II is located the lateral surface of lower ladder-shaped structure. The conductive steel ring adopts a thin-wall plug with the wall thickness of 1mm and made of stainless steel or low-carbon steel.
The method for synthesizing the polycrystalline diamond composite cutting pick by using the polycrystalline diamond composite cutting pick synthesis block comprises the following steps:
1) putting the pyrophyllite blocks and the pyrophyllite rings into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 3 multiplied by 10-2Heating to 350-400 ℃ below Pa, and preserving the heat at 350-400 ℃ for 20-25 h for later use;
2) putting the polycrystalline diamond composite cutting pick blank into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 6 multiplied by 10- 2Heating to 150-200 ℃ under Pa, preserving heat for 0.5-1 h at 150-200 ℃, then continuously vacuumizing and heating to 850-950 ℃ until the pressure in the furnace is stabilized at 3 x 10-3Stopping vacuumizing below Pa, filling mixed gas into the vacuum heating furnace at 850-950 ℃ until the pressure in the furnace is 100-150 Mbar, reducing the composite sheet blank for 4-6 h, and vacuumizing until the pressure in the furnace is 3 multiplied by 10-3Pa below; wherein:
the mixed gas is carbon dioxide and hydrogen;
the volume percentages of the carbon dioxide and the hydrogen are respectively 40-45% and 55-60%;
3) assembling the pyrophyllite hollow block, the pyrophyllite ring and the polycrystalline diamond composite cutting pick blank obtained in the step 1) and the step 2) together with other parts of the composite block of the polycrystalline diamond composite cutting pick to form a composite block;
4) and (3) placing the synthetic block obtained in the step 3) in a cubic press, applying pressure to the pyrophyllite block and the conductive pressure transfer layer, and when the pressure rises to 4-5 GPa, introducing 900-1600A current to the conductive steel ring I, wherein the current flows through the upper conductive sheet, the trapezoidal conductive column, the lower conductive sheet, the heating tube I, the connecting washer and the heating tube II in sequence and then flows out of the conductive steel ring II positioned below to form a current path, so that the heating tube sinters the polycrystalline diamond composite cutting tooth blank in the synthetic cavity, and finally obtaining the polycrystalline diamond composite cutting tooth product.
Further, in the step 4), the current is introduced and then the pressure is increased to 6-7 GPa, the heating temperature is kept for 5-15 min when the heating temperature is increased to 1400-1500 ℃, then the temperature of the cavity is reduced to 950-1000 ℃ at the cooling rate of 120-160 ℃/min, then the current is cut off, the heating is stopped, and meanwhile, the pressure of the cavity is slowly reduced to the normal pressure at the rate of 1.0-1.1 GPa/min, so that the sintering of the polycrystalline diamond composite cutting tooth is completed.
The polycrystalline diamond composite cutting pick obtained by the synthesis method.
The invention has the following beneficial effects:
1. the invention adopts analytically pure sodium chloride as an isolation layer and an isolation cap material to wrap the closed polycrystalline diamond compact bad material synthesis unit, and sodium chloride is molten at the synthesis temperature, so that the isostatic pressure transmission effect is achieved, and meanwhile, the volume of the molten sodium chloride can expand to offset the volume compression caused by high-temperature phase change of part of pyrophyllite, so that the pressure field in the synthesis cavity tends to be in a stable state.
2. Aiming at the problems that when a traditional synthetic block assembly structure is used for synthesizing a polycrystalline diamond composite cutting tooth, the quality of the synthesized polycrystalline diamond composite cutting tooth is easy to be unstable and the performance of the synthesized polycrystalline diamond composite cutting tooth is not high due to the fact that the length-diameter ratio of the traditional synthetic block assembly structure is large and is limited by a synthetic cavity structure, the synthetic block is heated by two heating pipes with different diameters, the diameters of the heating pipes are different, and then the upper cavity and the lower cavity in a synthetic cavity form a temperature difference, the temperature of a polycrystalline diamond layer of a blank in the synthetic cavity is higher than that of a hard alloy substrate end, and the problems that when the existing synthetic block assembly structure is used for synthesizing the polycrystalline diamond composite cutting tooth with.
3. The pyrophyllite block and the pyrophyllite ring meet the requirement of synthesizing high-grade polycrystalline diamond composite cutting teeth through vacuum roasting and reasonable process selection.
4. In the ultrahigh pressure and high temperature synthesis of the polycrystalline diamond composite cutting pick, the purity of the metal binding agent and the particle surface state of the diamond raw material directly influence the performance of the composite piece.
5. In the design of the conductive pressure transfer layer, the conductive steel ring adopts a thin-wall plug with the wall thickness of 1mm and made of stainless steel or low-carbon steel, dolomite and a peripheral sleeve leaf paraffin ring are filled in the middle of the conductive steel ring to ensure that reactants in a synthesis cavity are uniformly pressed and do not deform, and the heat transfer from two ends to the direction of a top hammer is reduced by utilizing the thin-wall structure of the conductive steel ring, so that the heat preservation of the two ends is realized and the hammer burning is avoided.
6. In the design of the conducting layer, the trapezoid conducting posts are arranged in the trapezoid holes of the heat insulation ring, the trapezoid conducting posts mainly have the function of conducting electricity, the trapezoid conducting posts have good heat conductivity, so that heat in the synthesis cavity is easily dissipated, and in order to effectively prevent heat dissipation in the synthesis cavity, the trapezoid conducting posts are made of graphite or molybdenum materials with certain resistance, so that the trapezoid conducting posts can generate heat while conducting electricity, and the heat dissipation of the synthesis cavity is hindered together with the heat insulation ring with the function of heat insulation.
Drawings
FIG. 1 is a schematic diagram of the structure of the synthesized block of the present invention.
In the figure, 1, a pyrophyllite block, 2, a pyrophyllite ring I, 3, a conductive steel ring I, 4, a dolomite core I, 51, an upper conductive sheet 52, a lower conductive sheet, 6, a trapezoidal conductive column, 7, a heat preservation ring, 8, a heating tube I, 9, a connecting washer, 10, a heating tube II, 11, an isolation layer, 12, a dolomite core II, 13, a conductive steel ring II, 14, a pyrophyllite ring II, 15, a heat preservation layer, 16, a polycrystalline diamond composite cutting tooth blank and 17, an isolation cap.
Detailed Description
In order to make the technical purpose, technical solutions and advantages of the present invention clearer, the technical solutions of the present invention are further described below with reference to the accompanying drawings and specific embodiments.
Example 1
As shown in fig. 1, a polycrystalline diamond composite cutting tooth synthesis block comprises a synthesis cavity for sintering a polycrystalline diamond composite cutting tooth blank 16 at high temperature and high pressure, wherein an isolation layer 11, a heating layer, a heat insulation layer 15 and a cylindrical shell are sequentially sleeved on the side wall of the synthesis cavity from inside to outside, a conductive layer and a conductive pressure transmission layer I are sequentially arranged at the top of the synthesis cavity from inside to outside, and a conductive pressure transmission layer II is arranged at the bottom of the synthesis cavity; the synthetic intracavity is equipped with polycrystalline diamond composite cutting tooth blank 16 and isolation cap 17, the top at polycrystalline diamond composite cutting tooth blank is established to the isolation cap, the layer that generates heat comprises heating tube I8, connecting washer 9 and heating tube II10, the external diameter of heating tube II10 is greater than heating tube I8, the external diameter of heating tube II10 is the same with connecting washer 9, the tube-shape shell is pyrophyllite piece 1.
Further, the conducting layer is composed of a trapezoid conducting post 6, a heat preservation ring 7 and conducting pieces, the thickness of the heat preservation ring 7 is the same as the height of the trapezoid conducting post 6, the heat preservation ring 7 is matched with the trapezoid conducting post 6, the heat preservation ring 7 is sleeved outside the trapezoid conducting post 6, the top and the bottom of the heat preservation ring 7 and the trapezoid conducting post 6 which are sleeved together are respectively provided with an upper conducting piece 51 and a lower conducting piece 52, the trapezoid conducting post 6 is made of graphite or molybdenum, the heat preservation ring 7 is made of dolomite, and the upper conducting piece 51 and the lower conducting piece 52 are both made of graphite plates or molybdenum plates.
Further, the conductive laminated layer I consists of a pyrophyllite ring I2, a conductive steel ring I3 and a dolomite core I4; conductive steel ring I3 cover is established outside dolomite core I4, pyrophyllite ring I2 cover is established outside conductive steel ring I3, conductive steel ring I3's external diameter equals the external diameter of heat preservation ring 7, pyrophyllite ring I2's external diameter equals the external diameter of heat preservation 15 (the top at heat preservation 15 is established to pyrophyllite ring I2 lid promptly).
Further, the conductive laminated layer II consists of a pyrophyllite ring II14, a conductive steel ring II13 and a dolomite core II 12; electrically conductive steel ring II13 overlaps and establishes outside dolomite core II12, pyrophyllite ring II14 overlaps and establishes outside electrically conductive steel ring II13, dolomite core II 12's external diameter is equal to the external diameter of isolation layer 11 (dolomite core II12 pads in the bottom of isolation layer 11 promptly), electrically conductive steel ring II 13's external diameter equals the external diameter of heating tube II10, pyrophyllite ring II 14's external diameter equals the external diameter of heat preservation 15 (pyrophyllite ring II14 pads in the bottom of heat preservation 15).
Further, the heating tube I8 and the heating tube II10 are made of graphite, iron-chromium-aluminum alloy, titanium or molybdenum, the connecting washer 9 is made of titanium, molybdenum, zirconium or tantalum, the isolation layer 11 and the isolation cap 17 are made of sodium chloride, and the heat insulation layer 15 is made of dolomite.
Further, the isolation layer 11 is a two-layer stepped structure, the two-layer stepped structure is an upper stepped structure and a lower stepped structure, the heating tube I8 is located on the outer side face of the upper stepped structure, the connecting washer 9 is located on the shoulder portion of the two-layer stepped structure, and the heating tube II10 is located on the outer side face of the lower stepped structure.
Example 2
A method of synthesizing a polycrystalline diamond compact pick using the synthesis block of embodiment 1, comprising the steps of:
1) putting the pyrophyllite block 1, the pyrophyllite ring I2 and the pyrophyllite ring II14 into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 3 multiplied by 10-3Heating to 380 ℃ below Pa, and keeping the temperature for 20 hours for later use;
2) placing the polycrystalline diamond compact pick blank 16 in vacuum sinteringIn the furnace, rough vacuum is carried out until the pressure in the furnace reaches 6 x 10-2Heating to 180 deg.C below Pa, maintaining for 1 hr, vacuumizing while heating to 900 deg.C until furnace pressure is stabilized at 3 × 10-3Pa below, stopping vacuumizing, introducing 150Mbar mixed gas into a vacuum heating furnace at 900 deg.C to reduce the composite sheet blank for 5h, and vacuumizing to 3 × 10-3Pa below; wherein:
the mixed gas is carbon dioxide and hydrogen;
the volume percentages of the carbon dioxide and the hydrogen are 45% and 55% respectively;
3) assembling the pyrophyllite block 1 obtained in the step 1) and the step 2), the pyrophyllite ring I2, the pyrophyllite ring II14, the heating tube I8, the heating tube II10, the polycrystalline diamond composite cutting pick blank 16 and other parts of the polycrystalline diamond composite cutting pick together to form a synthetic block;
4) putting the synthetic block obtained in the step 3) into a cubic press, applying pressure to the pyrophyllite block 1 and the conductive pressure transmission layer, when the pressure rises to 4.5GPa, the conducting steel ring I positioned above is electrified with 1200A current, the current sequentially passes through the upper conducting strip 51, the trapezoidal conducting column 6, the lower conducting strip 52, the heating tube I8, the connecting washer 9 and the heating tube II10, and then flows out from the conducting steel ring II13 positioned below to form a current path, sintering the polycrystalline diamond composite cutting pick blank 16 in the synthesis cavity by the heating tube, boosting the pressure to 6.5GPa, heating to 1500 ℃ and keeping the temperature for 10min, then, the temperature of the cavity is reduced to 1000 ℃ at the cooling rate of 140 ℃/min, and then, cutting off the current to stop heating, and simultaneously, slowly reducing the pressure of the cavity to normal pressure at the speed of 1.0GPa/min to complete sintering of the polycrystalline diamond composite cutting pick at high temperature and high pressure.
Example 3
A method of synthesizing a polycrystalline diamond compact pick using the synthesis block of embodiment 1, comprising the steps of:
1) putting the pyrophyllite block 1, the pyrophyllite ring I2 and the pyrophyllite ring II14 into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 3 multiplied by 10-3Heating to 350 ℃ below Pa, and keeping the temperature for 25 hours for later use;
2) placing the polycrystalline diamond composite cutting pick blank 16 in a vacuum sintering furnace, and roughly vacuumizing until the air pressure in the furnace reaches 6 multiplied by 10-2Heating to 150 deg.C below Pa, maintaining for 1 hr, vacuumizing while heating to 950 deg.C until furnace pressure is stabilized at 3 × 10-3Pa below, stopping vacuumizing, introducing mixed gas with internal gas pressure of 100Mbar into vacuum heating furnace at 950 deg.C to reduce the composite sheet blank for 6h, and vacuumizing to internal gas pressure of 3 × 10-3Pa below; wherein:
the mixed gas is carbon dioxide and hydrogen;
the volume percentages of the carbon dioxide and the hydrogen are 42% and 58% respectively;
3) assembling the pyrophyllite block 1 obtained in the step 1) and the step 2), the pyrophyllite ring I2, the pyrophyllite ring II14, the heating tube I8, the heating tube II10, the polycrystalline diamond composite cutting pick blank 16 and other parts of the polycrystalline diamond composite cutting pick together to form a composite block.
4) Putting the synthetic block obtained in the step 3) into a cubic press, applying pressure to the pyrophyllite block 1 and the conductive pressure transmission layer, when the pressure rises to 4GPa, 1600A current is introduced into the conductive steel ring I positioned above, and the current flows out from the conductive steel ring II13 positioned below through the lower conductive sheet 51, the trapezoidal conductive column 6, the lower conductive sheet 52, the heating tube I8, the connecting washer 9 and the heating tube II10 in sequence to form a current path, the heating tube heats the polycrystalline diamond composite cutting pick blank 16 in the synthesis cavity, the pressure is increased to 6GPa, the temperature is increased to 1400 ℃ and kept for 15min, then the temperature of the cavity is reduced to 950 ℃ at the cooling rate of 160 ℃/min, and then, cutting off the current to stop heating, and simultaneously, slowly reducing the pressure of the cavity to normal pressure at the speed of 1.0GPa/min to complete sintering of the polycrystalline diamond composite cutting pick at high temperature and high pressure.
Example 4
A method of synthesizing a polycrystalline diamond compact pick using the synthesis block of embodiment 1, comprising the steps of:
1) putting the pyrophyllite block 1, the pyrophyllite ring I2 and the pyrophyllite ring II14 into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 3 multiplied by 10-3Heating to 400 ℃ below Pa, and keeping the temperature for 25 h for later use.
2) Placing the polycrystalline diamond composite cutting pick blank 16 in a vacuum sintering furnace, and roughly vacuumizing until the air pressure in the furnace reaches 6 multiplied by 10-2Heating to 200 deg.C below Pa, maintaining for 0.5h, vacuumizing and heating to 850 deg.C until furnace pressure is stabilized at 3 × 10-3Pa below, stopping vacuumizing, introducing mixed gas with internal gas pressure of 120Mbar into vacuum heating furnace at 850 deg.C to reduce the composite sheet blank for 4 hr, and vacuumizing to internal gas pressure of 3 × 10-3Pa below; wherein:
the mixed gas is carbon dioxide and hydrogen;
the volume percentages of the carbon dioxide and the hydrogen are respectively 40% and 60%;
3) assembling the pyrophyllite block 1 obtained in the step 1) and the step 2), the pyrophyllite ring I2, the pyrophyllite ring II14, the heating tube I8, the heating tube II10, the polycrystalline diamond composite cutting pick blank 16 and other parts of the polycrystalline diamond composite cutting pick together to form a composite block.
4) Putting the synthetic block obtained in the step 3) into a cubic press, applying pressure to the pyrophyllite block 1 and the conductive pressure transmission layer, when the pressure rises to 5GPa, the conducting steel ring I positioned above is electrified with 900A current, the current flows out from the conducting steel ring II13 positioned below through the lower conducting strip 51, the trapezoidal conducting column 6, the lower conducting strip 52, the heating tube I8, the connecting washer 9 and the heating tube II10 in sequence to form a current path, the heating tube heats the polycrystalline diamond composite cutting pick blank 16 in the synthesis cavity, the pressure is increased to 7GPa, the temperature is increased to 1400 ℃ and is kept for 5min, then the temperature of the cavity is reduced to 980 ℃ at the cooling rate of 120 ℃/min, and then, cutting off the current to stop heating, and simultaneously, slowly reducing the pressure of the cavity to normal pressure at the speed of 1.1GPa/min to complete sintering of the polycrystalline diamond composite cutting pick at high temperature and high pressure.
Comparative test
Comparative example 1
Comparative example 1 the same preparation method as in example 2 was used, except that the synthesis block structure was different, except that: the composite block of comparative example 1 has the lower conductive sheet 52, conductive trapezoidal post 6 and insulating ring 7 of example 1 removed and the axial lengths of the associated components changed accordingly so that the composite block maintains a close structure of stacked layers.
Comparative example 2
Comparative example 2 the same preparation method as in example 2 was used, except that the synthesis block structure was different, except that: in the composite block of comparative example 2, the diameter of the heating tube I8, the connection washer 9 and the heating tube II10 are the same, and the radial dimensions of the related component isolation layer 11 and the conductive steel ring II13 are changed accordingly, so that the composite block maintains a tight structure of radial stacking.
Comparative example 3
Comparative example 3 the same preparation method as in example 2 was used, except that the synthesis block structure was different, except that: in the composite block of comparative example 3, the isolation layer 11 and the isolation cap 17 were all made of dolomite.
Comparative example 4
Comparative example 4 the same synthetic block structure as in example 2 was used, except that the preparation method was different, except that: in comparative example 4, pyrophyllite block 1, pyrophyllite ring I2, and pyrophyllite ring II14 were baked in a non-vacuum state (i.e., at room temperature and pressure).
Comparative example 5
Comparative example 5 the same synthetic block structure as in example 2 was used, except that the preparation method was different, and only the difference was that
Comprises the following steps: in comparative example 5, a pressure of 6.5GPa was applied, current was applied while pressurizing, the temperature was held at 1500 ℃ for 20min, and then heating was stopped by cutting off the current while the pressure was slowly reduced to normal pressure at a rate of 1.2GPa/min, thereby completing sintering.
The polycrystalline diamond composite cutting pick prepared in the example 2 and the comparative examples 1 to 5 are tested for wear resistance, impact resistance and thermal stability under the same test conditions, the conventional test methods in the field are adopted for the methods for testing the wear resistance, the impact resistance and the thermal stability, JB/T3235-2013 'method for measuring the abrasion ratio of the sintered artificial diamond compact' is adopted for testing the wear resistance, and a drop hammer impact method is adopted for testing the impact toughness (namely, a 4kg impact hammer freely falls at a height of 100cm, and the energy is used for impacting a sample to obtain an impact resistance value when micro cracks appear on the surface of the sample), and the statistical results are as follows:
Figure DEST_PATH_IMAGE001
as can be seen from the statistical results in the table above: compared with comparative examples 1 to 5, the polycrystalline diamond composite cutting pick prepared in examples 2 to 4 has the advantages that the abrasion ratio is improved by 29 to 67 percent, the impact resistance is improved by 30 to 100 percent, and the abrasion ratio and the impact toughness change are minimum after the polycrystalline diamond composite cutting pick is roasted for 2 hours at 750 ℃, so that the polycrystalline diamond composite cutting pick has better abrasion resistance, heat resistance and impact resistance.
Finally, it should be noted that: the above embodiments are merely illustrative and not restrictive of the technical solutions of the present invention, and any equivalent substitutions and modifications or partial substitutions made without departing from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims (8)

1. A polycrystalline diamond composite cutting tooth synthesis block comprises a synthesis cavity for sintering a polycrystalline diamond composite cutting tooth blank at high temperature and high pressure, wherein an isolation layer, a heating layer, a heat insulation layer and a cylindrical shell are sequentially sleeved on the side wall of the synthesis cavity from inside to outside; the synthetic intracavity is equipped with polycrystalline diamond composite pick blank and isolation cap, the top at polycrystalline diamond composite pick blank is established to the isolation cap lid, its characterized in that: the heating layer consists of a heating tube I, a connecting washer and a heating tube II, the outer diameter of the heating tube II is larger than that of the heating tube I, the outer diameter of the heating tube II is the same as that of the connecting washer, and the cylindrical shell is a pyrophyllite block; the conducting layer is composed of a trapezoid conducting post, a heat preservation ring and a conducting piece, the thickness of the heat preservation ring is the same as the height of the trapezoid conducting post, the heat preservation ring is matched with the trapezoid conducting post, the heat preservation ring is sleeved outside the trapezoid conducting post, the top and the bottom of the heat preservation ring and the trapezoid conducting post which are sleeved together are respectively provided with an upper conducting piece and a lower conducting piece, the trapezoid conducting post is made of graphite or molybdenum, the heat preservation ring is made of dolomite, and the conducting piece is made of a graphite plate or a molybdenum plate.
2. The polycrystalline diamond compact pick composite block of claim 1, wherein: the conductive laminated layer I consists of a pyrophyllite ring I, a conductive steel ring I and a dolomite core I; conductive steel ring I cover is established outside dolomite core I, pyrophyllite ring I cover is established outside conductive steel ring I, conductive steel ring I's external diameter equals the external diameter of heat preservation ring, pyrophyllite ring I's external diameter equals the external diameter of heat preservation layer.
3. The polycrystalline diamond compact pick composite block of claim 1, wherein: the conductive pressure transmission layer II consists of a pyrophyllite ring II, a conductive steel ring II and a dolomite core II; conductive steel ring II cover is established outside dolomite core II, pyrophyllite ring II cover is established outside conductive steel ring II, dolomite core II's external diameter equals the external diameter of isolation layer, conductive steel ring II's external diameter equals heating tube II's external diameter, pyrophyllite ring II's external diameter equals the external diameter of heat preservation.
4. The polycrystalline diamond compact pick composite block of claim 1, wherein: the heating tube I and the heating tube II are made of graphite, iron-chromium-aluminum alloy, titanium or molybdenum, the connecting gasket is made of titanium, molybdenum, zirconium or tantalum, the isolation layer and the isolation cap are made of sodium chloride, and the heat preservation layer is made of dolomite.
5. The polycrystalline diamond compact pick composite block of claim 1, wherein: the isolation layer is two-layer stair-shaped structure, and two-layer stair-shaped structure is last stair-shaped structure and lower ladder-shaped structure respectively, and heating tube I is located the lateral surface of last stair-shaped structure, and the connecting washer is located two-layer stair-shaped structure's shoulder, and heating tube II is located lower ladder-shaped structure's lateral surface.
6. A method of synthesizing a polycrystalline diamond compact pick using the polycrystalline diamond compact pick synthesis block of any one of claims 1 to 5, comprising the steps of:
1) putting the pyrophyllite blocks and the pyrophyllite rings into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 3 multiplied by 10-2Heating to 350-400 ℃ below Pa, and preserving the heat at 350-400 ℃ for 20-25 h for later use;
2) putting the polycrystalline diamond composite cutting pick blank into a vacuum sintering furnace, and vacuumizing until the air pressure in the furnace reaches 6 multiplied by 10-2Heating to 150-200 ℃ under Pa, preserving heat for 0.5-1 h at 150-200 ℃, then continuously vacuumizing and heating to 850-950 ℃ until the pressure in the furnace is stabilized at 3 x 10-3Stopping vacuumizing below Pa, filling mixed gas into the vacuum heating furnace at 850-950 ℃ until the pressure in the furnace is 100-150 Mbar, reducing the composite sheet blank for 4-6 h, and vacuumizing until the pressure in the furnace is 3 multiplied by 10-3Pa below; wherein:
the mixed gas is carbon dioxide and hydrogen;
the volume percentages of the carbon dioxide and the hydrogen are respectively 40-45% and 55-60%;
3) assembling the pyrophyllite hollow block, the pyrophyllite ring and the polycrystalline diamond composite cutting pick blank obtained in the step 1) and the step 2) together with other parts of the composite block of the polycrystalline diamond composite cutting pick to form a composite block;
4) and (3) placing the synthetic block obtained in the step 3) in a cubic press, applying pressure to the pyrophyllite block and the conductive pressure transfer layer, and when the pressure rises to 4-5 GPa, introducing 900-1600A current to the conductive steel ring I, wherein the current flows through the upper conductive sheet, the trapezoidal conductive column, the lower conductive sheet, the heating tube I, the connecting washer and the heating tube II in sequence and then flows out of the conductive steel ring II positioned below to form a current path, so that the heating tube sinters the polycrystalline diamond composite cutting tooth blank in the synthetic cavity, and finally obtaining the polycrystalline diamond composite cutting tooth product.
7. The method for synthesizing the polycrystalline diamond composite cutting tooth according to claim 6, wherein in the step 4), the pressure is increased to 6-7 GPa after current is introduced, the heating temperature is kept for 5-15 min when being increased to 1400-1500 ℃, then the temperature of the cavity is reduced to 950-1000 ℃ at the temperature reduction rate of 120-160 ℃/min, then the current is cut off, the heating is stopped, and meanwhile, the pressure of the cavity is slowly reduced to the normal pressure at the rate of 1.0-1.1 GPa/min, so that the sintering of the polycrystalline diamond composite cutting tooth is completed.
8. A polycrystalline diamond compact pick obtained by the method of synthesis recited in claim 6.
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