大单晶立方氮化硼的高温高压制备与表征

High-Pressure High-Temperature Synthesis and Characterization of Large Single Crystal of cBN

魏征

11849272

硕士

材料工程

王善民

2020-05-29

2020-07-08

哈尔滨工业大学

深圳

立方氮化硼（cBN）是一种硬度仅次于金刚石的超硬材料，具备多种优异的性能。作为重要的超硬半导体材料，cBN的单晶制备技术远远落后于金刚石，严重地阻碍了它在精密加工、第三代半导体、以及光谱器件上的应用和发展。为此，发展立方氮化硼大单晶制备技术迫在眉睫，也是我国超硬刀具技术实现突破的重要契机。因此，本项目拟发展立方氮化硼单晶的高温高压合成技术，突破现有技术与原理的瓶颈，发展cBN单晶高压合成方法与工艺，以制备出高品级大尺寸的cBN单晶体，为发展第三代半导体、光学器件和量子芯片等提供重要的材料载体。同时，就掺硼金刚石加热器的制备做了相应的研究，以期制备出超高温的掺硼金刚石加热器，以突破Kawai型（6-8式二级加压）高温高压装置的温度极限，为原位X射线观察提供便利，也为高压下材料的合成和研究提供实验设备支持。本文依托于国产DS6×10 MN铰链式六面顶压机，以hBN粉末作为主要原料，选取Mg3N2作为触媒材料，进行一系列合成cBN单晶的方法和工艺研究。主要研究内容为：cBN单晶的制备与提纯；研究不同合成工艺参数对cBN晶体合成效果的影响以及采用新型组装方式合成毫米级cBN单晶，为cBN单晶的工业化生产提供实验和理论基础。此外依托于德国沃根瑞特公司的Kawai型高温高压装置，制备超高温掺硼石墨加热管，并对其高温性能进行测试，以期突破二级加压高温高压装置3000 ℃温度极限。本文主要得到了以下结论：采用Mg3N2作为触媒材料，成功利用国产DS6×10 MN铰链式六面顶压机合成出了cBN晶体，且通过采用不同的合成工艺，确定了cBN单晶最佳合成工艺参数。通过3组对比实验，确定合成cBN单晶最佳的合成压力为5.5 GPa、合成温度为1500 ℃、合成时间为60 min，在该条件下，合成的cBN单晶产量达到了近90 %，尺寸达到了600 μm；且采用新型分层组装方式合成出了毫米级cBN单晶，最大单晶尺寸达到了1.5 mm，单晶的维氏硬度为53 GPa。通过自主研制的石墨加热器，成功突破了Kawai型高温高压装置的温度极限。研制的新型掺硼石墨加热器配合自制MgO八面体传压介质和CrO保温介质，成功将二级高压腔体内部温度加热至接近2000 ℃，并且通过外延法得到，新型二级高压加热组装可以成功实现3000 ℃的高温，且加热效率高，加热过程稳定，为接下来新型材料和超硬材料的合成制备和研究提供了良好的条件和支持。

Cubic boron nitride (cBN) is a superhard material with a hardness second only to diamond, with many excellent properties. However, as an important superhard semiconductor, cBN single-crystal preparation technology lags far behind that of diamond, which seriously hinders its application and development in precision machining, third-generation semiconductors, and spectroscopic devices. Hence, technological development for preparing cBN large single crystal is not only an urgent matter, but also an important opportunity for China's superhard industry to achieve breakthroughs. This project intends to improve high-temperature high-pressure technology for synthesizing large cBN single crystal, and prepare high-grade large-size cBN single crystal as important material carriers for third-generation semiconductors, optical devices, and quantum chips. In the meantime, research was done on the preparation of boron-doped graphite heaters to overcome the temperature limit of Kawai type two-stage high pressure apparatus. It will lend support to high-pressure experimental research in general, and in-situ synchrotron X-ray study in particular.This project relies on the domestic DS6 × 10 MN hinged six-sided cubic press, using hBN powder as the main raw material and Mg3N2 as the catalyst material, to conduct a series of comparative studies on the methods and processes for the synthesis of cBN single crystal. The main research contents are: the preparation and purification of cBN single crystal; studying the influence of different parameters - pressure, temperature, duration - on the production and the size of cBN crystal; and the synthesis of millimeter-sized cBN single crystal by new assembly method, which provides experimental and theoretical basis for the industrial production. In addition, the ultra-high temperature boron-doped graphite heater was prepared, and its performance was experimentally tested.Using Mg3N2 as the catalyst material, we have successfully synthesized cBN single crystals using a domestic DS6 × 10 MN hinged six-sided cubic press, and the optimal synthesis parameters were determined through three sets of comparative experiments. Under optimal condition (at 5.5 GPa and 1500 ℃ for 60 min), the yield reached nearly 90%, and the size of the single crystal was up to 600 μm; The new layered assembly was used to synthesize the millimeter-sized cBN single crystal, with the maximum sizereaching 1.5 mm. The Vickers hardness of the single crystal was 53 GPa.The newly developed boron-doped graphite heater, together with the self-made MgO octahedral pressure transmission medium and CrO insulator successfully achieved an internal temperature of nearly 3000 ℃. High heating efficiency and stable process provide good conditions and support for the subsequent synthesis and research of new materials.

高温高压 立方氮化硼单晶 触媒 合成工艺 石墨高温加热器

high temperature and high pressure cubic boron nitride single crystal catalyst synthesis process high temperature graphite heater

中文

联合培养

南方科技大学

魏征. 大单晶立方氮化硼的高温高压制备与表征[D]. 深圳. 哈尔滨工业大学,2020.