排序方式: 共有107条查询结果,搜索用时 62 毫秒
41.
以有限元法为理论分析手段模拟分析了国产六面顶压机配套顶锤内部的温度场和热应力分布.探寻出了XKY-6×2000 MN型六面顶压机顶锤内部的温度场分布以及热应力取值.模拟结果表明加热顶锤内部温度分布不均匀,不均匀的温度分布产生了热剪切应力,热剪切应力峰值达到0.62 GPa,分布在41.5°小斜面上.加热顶锤内部的剪切应力值较非加热锤内部的剪切应力值高出18.0%.模拟分析结果与金刚石的高压合成实验事实相符,在理论上解释了加热顶锤使用寿命较非加热顶锤使用寿命短的原因,此项工作对于提高大顶锤使用寿命,降低生产
关键词:
热应力
顶锤
有限元法
工业金刚石 相似文献
42.
Synthesis of large diamond crystals containing high-nitrogen concentration at high pressure and high temperature using Ni-based solvent by temperature gradient method
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This paper reprots that with Ni-based catalyst/solvent and with a dopant of NaN 3,large green single crystal diamonds with perfect shape are successfully synthesized by temperature gradient method under high pressure and high temperature in a China-type cubic anvil high-pressure apparatus (SPD-6×1200),and the highest nitrogen concentration reaches approximately 1214-1257 ppm calculated by infrared absorption spectra.The synthesis conditions are about 5.5 GPa and 1240-1300 C.The growth behaviour of diamond with high-nitrogen concentration is investigated in detail.The results show that,with increasing the content of NaN 3 added in synthesis system,the width of synthesis temperature region for growth high-quality diamonds becomes narrower,and the morphology of diamond crystal is changed from cube-octahedral to octahedral at same temperature and pressure,the crystal growth rate is slowed down,nevertheless,the nitrogen concentration doped in synthetic diamond increases. 相似文献
43.
Different effect of NiMnCo or FeNiCo on the growth of type-Ⅱa large diamonds with Ti/Cu as nitrogen getter
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In order to synthesize high-quality type-Ⅱa large diamond, the selection of catalyst is very important, in addition to the nitrogen getter. In this paper, type-IIa large diamonds are grown under high pressure and high temperature(HPHT) by using the temperature gradient method(TGM), with adopting Ti/Cu as the nitrogen getter in Ni_(70)Mn_(25)Co_5(abbreviated as NiMnCo) or Fe_(55)Ni_(29)Co_(16)(abbreviated FeNiCo) catalyst. The values of nitrogen concentration(N_c) in both synthesized high-quality diamonds are less than 1 ppm, when Ti/Cu(1.6 wt%) is added in the FeNiCo or Ti/Cu(1.8 wt%) is added in the NiMnCo. The difference in solubility of nitrogen between both catalysts at HPHT is the basic reason for the different effect of Ti/Cu on eliminating nitrogen. The nitrogen-removal efficiency of Ti/Cu in the NiMnCo catalyst is less than in the FeNiCo catalyst. Additionally, a high-quality type-Ⅱa large diamond size of 5.0 mm is obtained by reducing the growth rate and keeping the nitrogen concentration of the diamond to be less than 1 ppm, when Ti/Cu(1.6 wt%) is added in the FeNiCo catalyst. 相似文献
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结合高能球磨和高温高压实验技术,制备了块体TiN/TiB2纳米复合材料。通过X射线衍射和拉曼光谱对材料的微观结构进行了研究。结果表明,采用金属Ti和六方BN为原料,在球磨过程和高温高压实验过程中,TiN先于TiB2形成,球磨70 h后有少量的纳米晶TiN开始形成。在高温高压实验中,在样品腔的合成温度低于1 300 ℃时,没有TiB2出现;当温度达到1 300 ℃后,合成出了TiN和TiB2的复合材料。对所合成的块状材料的热膨胀性和导电性能进行了测试。 相似文献
46.
Zirconium nitride powders with rock salt structure (γ-ZrNx) are prepared by mechanical milling of a mixture of Zirconium and hexagonal boron nitride (h-BN) powders. The products are analysed by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy (ITS). The formation mechanism of γ-ZrNx by ball milling technique is investigated in detail. N atoms diffuse from amorphous BN (a-BN) into Zr to form Zr(N) solid solution alloy, then the Zr(N) solid solution alloy decomposes into γf-ZrNx. No ZrB2 is observed in the as-milled samples or the samples annealed at 1050° C for 2h. 相似文献
47.
Micron grade boron-doped diamond crystals with octahedral morphology are successfully synthesized in a Fe-Ni- C-B system under high pressure and high temperature (HPHT). The effects of the additive boron on synthesis conditions, nucleation and growth, crystal morphology of diamond are studied. The synthesized micron grade diamond crystals were characterized by optical microscope (OM), scanning electron microscope (SEM), x-ray diffraction (XRD) and Raman spectroscopy. The research results show that the V-shaped section of synthetic diamond moves downwards to the utmost extent due to 0.3a wt% (a is a constant.) boron added in the synthesis system. The crystal colour is black, and the average crystal size is about 25μm. The crystal faces of synthetic diamond are mainly (111) face. The synthesis of this kind of diamond is few reported, and it will have important and widely applications. 相似文献
48.
温度梯度法生长宝石级金刚石单晶过程中,当籽晶无法完全吸收由高温端扩散下来的碳源时,多余碳源的不同析出形式(再结晶石墨或者自发核)对晶体生长速度有明显的影响。当大量多余碳源以再结晶石墨形式析出时,和以金刚石自发核形式析出不同,晶体的生长速度受到较为明显的抑制作用。例如,以NiMnCo触媒为例,随着合成温度的提高,当多余碳源不再以金刚石自发核形式析出,而是以大量片状再结晶石墨形式围绕在晶体周围时,晶体的生长速度从相对低温时的约3.0mg/h降到较高温度时的1.0mg/h;此外,随着合成压力由5.5GPa降到5.2GPa,晶体生长速度由3.0mg/h降到1.0mg/h,多余碳源析出形式也由金刚石自发核变化为再结晶石墨。 相似文献
49.
Reaction mechanism of metal and pyrite under high-pressure and high-temperature conditions and improvement of the properties
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Pyrite tailings are the main cause of acid mine wastewater. We propose an idea to more effectively use pyrite, and it is modified by exploiting the reducibility of metal represented by Al under high-pressure and high-temperature (HPHT) conditions. Upon increasing the Al addition, the conductivity of pyrite is effectively improved, which is nearly 734 times higher than that of unmodified pyrite at room temperature. First-principles calculations are used to determine the influence of a high pressure on the pyrite lattice. The high pressure increases the thermal stability of pyrite, reduces pyrite to high-conductivity Fe7S8 (pyrrhotite) by Al. Through hardness and density tests the influence of Al addition on the hardness and toughness of samples is explored. Finally we discuss the possibility of using other metal-reducing agents to improve the properties of pyrite. 相似文献
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