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CN-122006583-A - Hexahedral top press for artificial diamond and cavity temperature heating method

CN122006583ACN 122006583 ACN122006583 ACN 122006583ACN-122006583-A

Abstract

The invention relates to the technical field of hexahedral top presses and discloses a hexahedral top press and a cavity temperature heating method for artificial diamond, which comprise six bearing beams and main top hammers which are hydraulically slid and telescopic along the bearing beams, wherein the main top hammer head section is provided with auxiliary top hammers which are hydraulically slid and telescopic, the head ends of the auxiliary top hammers are protruded out of the head end surface of the main top hammers, when the main top hammers are assembled, the auxiliary top hammers are in a contracted state and gaps are reserved between adjacent auxiliary top hammers, a diamond synthesis stage and the auxiliary top hammer out are used for exerting pressure, and a post-synthesis cooling stage and the auxiliary top hammers are folded.

Inventors

  • PENG XIANWEI
  • CHEN LING
  • ZHANG QING
  • YU DONG

Assignees

  • 河南平煤神马超硬材料股份有限公司

Dates

Publication Date
20260512
Application Date
20260410

Claims (10)

  1. 1. A hexahedral top press for artificial diamond comprises six pressure beams (1) and main top hammers (2) which hydraulically slide and stretch along the pressure beams (1), and is characterized in that the head section of the main top hammers (2) is provided with auxiliary top hammers (3) which hydraulically slide and stretch, the head end of each auxiliary top hammer (3) protrudes out of the end face of the head end of the main top hammer (2), when the main top hammers (2) are assembled, the auxiliary top hammers (3) are in a contracted state, gaps are reserved between the adjacent auxiliary top hammers (3), a diamond synthesis stage and the auxiliary top hammers (3) stretch out to apply pressure, and a post-synthesis cooling stage and the auxiliary top hammers (3) are folded.
  2. 2. The hexahedral top press for artificial diamond according to claim 1, wherein a first oil cavity (5) is arranged in the pressure-bearing beam (1), the inner end of the main top hammer (2) extends into the first oil cavity (5) and is connected with a first piston part (4), and two ends of the first oil cavity (5) are respectively connected with a first oil duct (6) and a second oil duct (7).
  3. 3. A cubic press for artificial diamond according to claim 2, wherein a second oil chamber (9) is provided in the main jack hammer (2), the inner end of the auxiliary jack hammer (3) extends into the second oil chamber (9) and is connected with a second piston part (8), and two ends of the second oil chamber (9) are respectively connected with a third oil duct (10) and a fourth oil duct (13).
  4. 4. A cubic press for artificial diamond according to claim 3, wherein an oil pipe (11) connected with the third oil passage (10) is arranged in the first oil chamber (5), an oil delivery hole (12) communicated with the second oil chamber (9) is arranged in the main jack hammer (2), and the oil pipe (11) extends into the oil delivery hole (12) and is in sliding seal with the inner wall of the oil delivery hole (12).
  5. 5. The hexahedral top press for artificial diamond according to claim 1, wherein the center of the end face of the head end of the main top hammer (2) is provided with a boss (14), the auxiliary top hammer (3) slides through the center of the boss (14), the head end of the auxiliary top hammer (3) is attached to the outer side face of the boss (14) when the main top hammer (2) is assembled, and the attached face is parallel to the end face of the head end of the main top hammer (2).
  6. 6. A cubic press for artificial diamond according to claim 5, wherein the boss (14) is provided with an annular stepped groove (15) at the center thereof, and the end of the sub-jack hammer (3) is provided with an annular stepped stage (16) which is fitted with the annular stepped groove (15) toward the side of the annular stepped groove (15).
  7. 7. A cubic press for synthetic diamond according to claim 1, characterised in that the main rams (2) are each provided with a cooling channel (17).
  8. 8. A cavity temperature heating method for a hexahedral press for synthetic diamond according to any one of claims 1 to 7, wherein the cavity temperature heating method comprises the steps of: Step one, heating preparation, namely selecting two auxiliary top hammers (3) which are arranged oppositely from six auxiliary top hammers (3) as conductive top hammers; Step two, die assembly and pressurization, namely controlling six main top hammers (2) to synchronously die assembly on six shafts, pressurizing in stages to preset synthetic pressure of 5-8GPa, maintaining the pressure until the pressure fluctuation is less than or equal to +/-0.1 MPa, and completing the sealing and pressure stabilization of a synthetic cavity; step three, graded gradient heating, namely starting a low-voltage high-current power supply and heating the inner cavity by adopting a sectional heating mode; cooling and pressure relief, namely cooling by adopting a stepped power-down mode after constant temperature growth is finished, wherein the first stage is reduced to 50% of target power at the rate of 50-80kW/min for 3-5min, the second stage is reduced to 0kW at the rate of 30-50kW/min for 2-10min, and the pressure relief is synchronously carried out in the cooling process, so that the temperature and the pressure of the cavity are synchronously reduced; And fifthly, after the pressure relief is finished, returning the top hammer, taking out the synthetic block, and cleaning the synthetic cavity.
  9. 9. The method of heating the cavity temperature of a cubic press for synthetic diamond according to claim 8, wherein the third step comprises the steps of: A preheating and heating section, wherein the heating power is linearly increased at the speed of 50-100kW/min for 3-8min, so that the temperature of the synthesis cavity is increased to 800-1000 ℃; A rapid heating section, wherein the heating rate is adjusted to 100-200kW/min, the heating time lasts for 2-5min, and the temperature of the cavity is increased to 1350-1450 ℃ of target growth temperature; and a constant temperature growth section, wherein the heating power is dynamically adjusted in a fine mode, so that the temperature of the cavity is stabilized within a target temperature, and the temperature of the main top hammer (2) is controlled to be less than or equal to 80 ℃.
  10. 10. The method of heating a chamber temperature of a cubic press for synthetic diamond according to claim 8, wherein the pressure relief rate in the fourth step is controlled to be 0.5 to 1.0GPa/min.

Description

Hexahedral top press for artificial diamond and cavity temperature heating method Technical Field The invention relates to the technical field of hexahedral top presses, in particular to a hexahedral top press for artificial diamond and a cavity temperature heating method. Background The hexahedral top press is key equipment for simultaneously applying ultrahigh pressure and high temperature to the central cavity from X, Y, Z to six directions, mainly adopts a hinge structure, forms high-pressure and thousands of DEG C high-temperature environment in the cavity by synchronous propulsion of six hydraulic top hammers, is core equipment for producing artificial diamond, cultivating diamond, cubic boron nitride and other superhard materials, and is also widely applied to the scientific research fields of high-pressure physics and the like. The working principle of the hexahedral top press is that six top hammers vertically pressurize from six faces of the pyrophyllite cube, and sealing edges with triangular sections are formed on edges of the pyrophyllite cube through small oblique angles around the hammer faces. Pyrophyllite has better fluidity under high pressure, and the pressure field in the cavity is kept relatively balanced. The pyrophyllite flows under high pressure and has certain viscosity, and the pyrophyllite of the sealing edge seals the material in a cavity formed by the top hammer by virtue of the wedge-shaped structure of the sealing edge and the friction force. The sealing edge formed by pyrophyllite, such as a wedge-shaped object, is inserted into the gap, and the extrusion force applied to the small bevel edge of the top hammer in the pressure-retaining stage is far greater than the pressure of the top hammer surface. The diamond synthesis process is to increase the pressure to the required value and raise the temperature for synthesis. The density and volume of the graphite are gradually increased and the volume of the graphite is gradually reduced along with the conversion of graphite to diamond, and the pressure in the cavity is required to be kept above 5GPa for the conversion to be continuously carried out. At present, the lining pipe is made of a material with high expansion and low heat conductivity, the expansion of dolomite is utilized to compensate the volume shrinkage in diamond synthesis, and the fluidity of pyrophyllite at the sealing edge is utilized to enable the top hammer to advance, but when the diamond synthesis condition is reached, the sealing edge is formed, the advancing of the top hammer inevitably causes the pressure of the sealing edge to be larger, the sealing edge is thinner by virtue of the fluidity of the pyrophyllite, and the advance of the hammer is blocked. The pressure at the sealing edge is far greater than the threshold value born by the pyrophyllite crystal structure, the material of the sealing edge undergoes phase change under high pressure, and the fluidity is poor. Resulting in a higher pressure at the sealing edge than the internal pressure of the cavity. The distance that the top hammer needs to advance is more, and the pressure difference between the top hammer surface center and the small inclined surface of the sealing edge is large, and the pressure difference easily causes the top hammer to bulge inwards to deform, so that the tensile stress outwards along the hammer surface is increased. When the tensile stress exceeds the threshold value which can be born by the top hammer, the hammer surface can crack, and even blasting is caused. When the synthesis is completed, the pressure difference between the top hammer surface center and the sealing edge is larger, the material is further contracted in the cooling process, and the top hammer surface generates tensile stress to be increased, so that the pressure unevenness of the top hammer surface exceeds the top hammer threshold value, and the top hammer cracking phenomenon is caused. Disclosure of Invention The present invention is directed to solving at least one of the above problems of the prior art and providing a hexahedral press for synthetic diamond and a cavity temperature heating method. In order to achieve the above purpose, the present invention provides the following technical solutions: the hexahedral top press for the artificial diamond comprises six pressure bearing beams and main top hammers which hydraulically slide and stretch along the pressure bearing beams, wherein the main top hammer head section is provided with auxiliary top hammers which hydraulically slide and stretch, the head ends of the auxiliary top hammers protrude out of the end face of the head end of the main top hammer, when the main top hammers are assembled, the auxiliary top hammers are in a contracted state and a gap is reserved between the adjacent auxiliary top hammers, the diamond synthesis stage and the auxiliary top hammer out exert pressure, and the auxiliary top hammers are folded in the post-synthesis coo