铰链式六面顶压机一级压腔增压组装的设计及其温压标定

DESIGN OF THE HYBRID CELL ASSEMBLY FOR CUBIC PRESS AND ITS PRESSURE AND TEMPERATURE CALIBRATION

宋国柱

11849290

硕士

材料工程领域工程

赵予生

2020-05-29

2020-07-20

哈尔滨工业大学

深圳

高压物理是在超高压条件下研究物质的物理性能的一门学科，几乎包含凝聚态物理的所有研究方向，并能够与材料学、化学、地学等诸多学科产生广泛的交叉研究。静高压设备是进行高压研究的基础，在所有的静高压设备中，六面顶压机因为具有超大样品腔体、操作简单、成本低廉、生产效率高等优点，非常适合进行工业生产以及根据需要在高温高压条件下制备大尺寸样品，因此被广泛应用于工业生产领域以及各科学研究领域。但是六面顶压机一级压腔的压力一直被限制在6 GPa 以内，这严重阻碍其应用领域的拓展，所以，在不牺牲腔体尺寸的的条件下提高六面顶压机的压力极限具有非常重要的科学和工程意义。本文首先基于国产铰链式六面顶压机设计了一种新的增压方案，即在带有12条密封边的异形叶蜡石块的六个面分别嵌入一个由高体弹模量的材料制成的四棱台增压块，并在增压块与压机的一级碳化钨压砧之间用叶蜡石片进行分隔用以保护压砧以及保温，组合成为一个混合传压介质组装，组装腔体内的其他组成部分如加热组件等也做出相应的调整。分别选用碳化钨（WC，体弹模量为380 GPa ）和ZrO2（体弹模量为90 GPa）作为增压材料，加工出预密封边−WC增压块组装和预密封边− ZrO2增压块组装。之后完成了对六面顶压机一级压腔的预密封边−WC增压块组装、预密封边− ZrO2增压块组装以及常规组装的压力标定，发现这三种组装的压力效率依次递减，增压块组装明显压力效率要高于常规组装，这是因为增压组装中增压块的加入大大提高了传压块整体的体弹模量，而体弹模量越高则压力效率也会越高；再者，增压块可以充分地抑制叶蜡石的流动而将大部分叶蜡石用于给腔体加压，同样对压力效率的提升有很大帮助。对腔体压力-外部载荷的关系曲线进行适当延伸，发现常规组转的压力极限为6 GPa，而预密封边−WC增压块组装样品腔的压力可以稳定升高到8 GPa 以上甚至冲极限可以达到9 GPa。其次也分别完成了上述三种六面顶压机一级压腔组装的温度标定实验，三种组装中，常规组装加热效率最高，预密封边−ZrO2增压块组装与常规组装相差无几，而预密封边−WC增压块组装加温效率较低，只有常规组装的62 %。其原因是加热效率与传压介质的导热系数有关，导热系数越高，加热效率越低，ZrO2的导热系数与叶蜡石接近，而WC的导热系数是叶蜡石的30倍。虽如此，预密封边−WC增压块组装的腔体温度仍然可以轻松达到2500 ℃ 以上，这足以满足绝大多数高压研究对于温度的要求。综合压力效率、温度效率以及组装运行的稳定性等因素，最终选定WC作为铰链式六面顶压机的预密封边−增压块一级压腔增压组装的增压材料，新的组装可以在8 GPa 以上高压、2500 ℃ 高温下稳定运行，必要时甚至可以用来冲击9 GPa的极限压力。使用新的一级压腔预密封边−增压块组装在6.5 MN、3 kW（对应腔体8 GPa、2000 K）的条件下对hBN进行高温高压实验，实现了hBN到cBN的直接转化，成功制备了直径为12 mm、高为5 mm的聚晶立方氮化硼样品。

High-pressure physics is a discipline that studies the physical properties of materials under ultra-high pressure. It contains almost all research directions of condensed matter physics and is capable of a wide range of interdisciplinary studies with materials science, chemistry, geology, and many other disciplines. High-pressure equipment is the basis for high-pressure research. Among all high-pressure equipment, the cubic press is suitable for production of large-size samples under high-temperature and high-pressure conditions and is widely used in industrial production and various scientific research fields because of its excellent performances such as large sample chamber, simple operation, low cost, high production efficiency, etc. However, the pressure of the cubic press has been limited to less than 6 GPa, which seriously prevents it from playing a more important role, thus, it is of great significance to increase the pressure limit of cubic press without sacrificing the chamber size. This article mainly completed the following content:A newly hybrid cell assembly is designed for cubic press, that is, the pyrophyllite pressure-transmitting medium block is embedded with six Tungsten Carbide (WC) pressure-enhancing blocks, the pressure-enhancing block and the first-stage Tungsten Carbide (WC) anvil are separated by pyrophyllite to protect the anvil and heat preservation. The pressure calibration of the hybrid cell assembly and the conventional assembly of cubic press was completed. The pressure efficiency of the hybrid cell assembly is much higher the that of the conventional assembly, the reason is that the addition of the WC blocks greatly improves the overall bulk modulus of the pressure-transmitting block, and the higher the bulk Modulus, the higher the pressure efficiency. Secondly, it is found that the pressure limit of the conventional assembly is 6 GPa, which is consistent with the previous report, and the pressure of the hybrid cell assembly can be raised higher than 8 GPa or even 9 GPa. The temperature calibration experiments for both assemblies were also finished. It was found that the heating efficiency of the hybrid cell assembly is much lower, only 62% of the conventional assembly, because of the high thermal conductivity of WC. Nevertheless, the temperature of the hybrid cell assembly can easily reach 2500 ℃, which is enough to meet the temperature requirements of most high-pressure studies.Ultrahard nano-polycrystalline cBN has been successfully synthesized by direct conversion of hBN above 8 GPa and 2000 ºC. Using the newly designed cell, the cubic device can be rousingly and safely implemented above 8 GPa and 2500 ºC with a centimetre-sized sample volume, which offers lots of new possibilities for discovery of new materials with advanced properties and exotic physics.

高压 六面顶大腔体压机 增压组装 超硬材料

high pressure cubic press hybrid cell assembly super hard materials

中文

联合培养

南方科技大学

宋国柱. 铰链式六面顶压机一级压腔增压组装的设计及其温压标定[D]. 深圳. 哈尔滨工业大学,2020.