六面顶压机加载下高温高压静水压声速测量技术及应用研究

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	六面顶压机加载下高温高压静水压声速测量技术及应用研究
	王志刚
导师	周文戈 ; 刘永刚
	2012
学位授予单位	中国科学院研究生院
学位授予地点	北京
学位名称	博士
学位专业	矿物学岩石学矿床学
关键词	高温高压六面顶压机声速测量宽带频谱法液体声速一级压标
摘要	过去的几十年，六面顶压机加载下的声速测量研究已经取得了巨大的进步，是高压物理、地球物理、超硬材料等领域普遍采用的研究手段，广泛用于金属、矿物、岩石、等材料的弹性性质研究。但声速测量技术方面仍存在诸多问题，包括样品所处静水压环境的问题、被测材料的频散问题、液体声速测量问题、压力温度准确性的问题等。若样品处于准静水压或非静水压环境，样品内存在较大的剪切应力，导致样品发生塑性形变，剪切模量较小的材料会发生严重塑性形变，单晶材料会发生破裂，最终导致声速测量的失败；声波在材料中传播时，声波的衰减系数与频率相关，导致不同频率的声波速度不同，即频散关系，而脉冲回波法一直难以测量高压下材料的声速频散关系；由于液体具有较好的流动性，大腔体压机加载下，液体难以密封及厚度难以测量，一直未见高温高压液体声速测量的报道，仅通过DAC加载下布里渊散射测量方法获得液体声速；大腔体压机加载下样品腔内的压力常常通过压标材料的相变来进行标定，通过热电偶直接测量样品腔内的温度，但是在固定压力加热的过程中，样品组装发生软化、体积膨胀等导致样品腔内的压力随温度升高而变化。以上问题影响着声速测量结果的精确度。本次论文的主要任务是在已有的六面顶压机加载下声速测量技术的基础上，利用新的手段和方法，以建立起更可靠更完善的声速测量技术，获得可靠的高温高压声速数据。论文主要包括四个方面，高温高压静水压声速测量技术研究、宽带频谱法应用于声波信号处理、液体声速测量以及六面顶压机加载下的一级压力标准研究设想。高温高压准静水压环境下测量声速时，由于剪应力的存在，剪切模量较小的多晶材料易发生塑性形变，使得样品长度难以估计，单晶样品易发生破裂，从而导致声速测量的失败。我们将设计满足高温高压静水压声速测量的样品组装，使用液体作为传压介质，确保样品处于完全静水压环境，高压下样品仅发生弹性形变。充分利用铋的已知相图，随着温度压力的变化，铋相变时声速发生突变，利用这一特点，以实现样品腔内的温度和压力的标定。固定压力升高温度过程中，充分利用铋的多相变的特点，给出了样品组装的热压贡献。声速测量结果与前人的实验结果具有较好的一致性。经过实验验证，该静水压组装设计合理，可用于更广泛的材料的高温高压声速研究。声波在介质中传播时，声波的传播速度与声波频率相关。基于脉冲回波法的宽带频谱法技术，可以测量有效带宽内的声波频率与速度的关系。本次研究中，利用宽带频谱法处理了六面顶压机静水压加载环境下测量了Z切石英的的声信号。压力至4.7GPa，一次实验中，同时获得纵波和横波的声速。通过对接收的声信号进行傅里叶变换，得到声信号的相位谱，经过相位展开计算，得到声速与频率的关系。高压下测量得到的弹性常数与前人的实验结果进行了对比，具有较好的一致性。液体声速测量一直是大腔体压机加载下声速测量的难点。本次研究，设计了满足液体声速测量研究的样品组装，测量了高温高压下水/冰的声速，压力温度至4.2GPa和500K。利用冰Ⅶ相的熔化线及室温水的固化压力，标定了样品腔内的压力。声速测量结果与前人的布里渊散射结果进行了对比，室温高压声速和熔化线上的声速均符合较好。可以认为，该液体声速测量组装具有很好的可靠性，可用于更广泛的液体声速研究。基于六面顶压机加载已经发展的高温高压静水压声速测量技术和高温高压液体声速测量技术，我们提出了六面顶压机加载下的一级压力标准研究设想，设计了在同时测量纵波/横波声速的基础上，满足长度测量的样品组装。依据高压下的密度-声速关系，试图建立一级压力标准。这一研究设想，以简单的方式，拟实现一级压力标准的研究，并将一级压力标准的研究范围扩展至了非透明固体材料与液体材料。经过以上问题的研究，六面顶压机加载下的声速测量技术得到了进一步的发展，研究对象范围从单一的硬材料扩展至软材料、单晶材料及液体等几乎全部的固体和液体材料，样品腔内的压力和温度更加准确，声速的测量精度得到进一步提高，并有望实现一级压力标准的研究。
其他摘要	In the past several decades, ultrasonic measurements on large-volume cubic apparatus have made great progress, but many problems still exist in ultrasonic measurements under high temperature and high pressure (HTHP), such as the hydrostatic circumstance of sample, processing of ultrasonic signal based on pulse echo method, the ultrasonic velocity measurement of liquid, the accuracy of experimental pressure and temperature so on. In the quasi-hydrostatic or non-hydrostatic pressure circumstance, there exists shear stress in the sample. Material with small shear modulus will distort greatly, and single-crystal materials will be broken, which lead to the failure of ultrasonic measurement. Not only the attenuation ratio of ultrasonic wave traveling across the sample is related with the frequency, the ultrasonic velocity is also changing with the frequency. The ultrasonic dispersion under high pressure is difficult to be measured. Sealing liquid and measuring the length of liquid is a hard task on large-volume cubic apparatus because of the high diffusion ability of liquids. There is very few papers related with liquid ultrasonic measurement under high pressure, and ultrasonic velocity data of liquid under high pressure in GPa ranges can only be achieved by Brillouin scatting technique on diamond anvil cell (DAC). The pressure of sample cell on large-volume apparatus is generally calibrated by phase transition of materials, and the temperature is calibrated only by thermocouple. As sample assembly will be softened and its volume will expand while heating at fixed pressure, the real pressure of sample cell will be hard to know. In this thesis, we try to solve these problems mentioned above, and ultrasonic measurement with higher precision will be set up step by step by using new methods. This thesis includes four parts, the first is about ultrasonic measurement under hydrostatic pressure and high temperature, the second is about a broadband spectroscopy method for ultrasonic velocity measurement under high pressure, the third is about ultrasonic measurement of liquid under HTHP and a proposal for primary pressure calibration on large-volume cubic apparatus as the final part. Under HTHP experiments, materials of small shear modulus will deform easily, and the length of sample can be hardly predicted which lead to failure of ultrasonic velocity measurement. In this thesis, a hydrostatic assembly of sample for ultrasonic measurements is designed under HTHP, which can prevent plastic deformation of sample occurring. According to abrupt change of travel time of sample across different phase boundary of bismuth, the correspondent relation of sample pressure and oil pressure of multi-anvil apparatus can be calibrated, and the relation of sample temperature and temperature measured by thermocouple can also be determined. Sample pressure under high temperature is also determined by ultrasonic results. It is believed that the new sample assembly of hydrostatic pressure is valid and feasible for ultrasonic experiments under HTHP. A broadband spectroscopy method is proposed to measure the ultrasonic wave phase velocity of Z-cut quartz under high pressure up to 4.7GPa. The sample is in a hydrostatic circumstance under high pressure, and we can get longitudinal wave and shear wave signals simultaneously in our work. By Fast Fourier Transform (FFT) of received signals, the spectrum and phase of the received signals could be got. After unwrapping the phase of the received signals, the travel time of ultrasonic wave in the sample could be obtained, and the ultrasonic wave phase velocity could also be resolved after data processing. The elastic constant of measurement under high pressure is also compared with previous studies. This broadband spectroscopy method is a valid method to get ultrasonic wave travel parameters, and it could be applied for elasticity study of materials under high pressure. A new assembly for ultrasonic measurements of water and ice on multi-anvil apparatus has been designed in this study, and the ultrasonic longitude velocities of water and ice up to 4.2GPa and 500K are achieved. The pressure of sample is calibrated by the melting curve of ice Ⅶ and transformation pressure of liquid to solid at ambient temperature. The sound velocities of this study are consistent with previous results by Brillouin scatting. It is believed that our system of ultrasonic measurements is reliable, and it is worth to be used for studying more liquids. Primary calibration on multi anvil apparatus is proposed based on the technique of ultrasonic measurement under hydrostatic pressure and high temperature and ultrasonic measurement of liquid under HTHP. A new sample assembly which can satisfy length and ultrasonic measurement simultaneously is designed. The primary calibration will be set up by the density-ultrasonic velocity relation. It is a very simple method to achieve primary calibration, and the object of study will expand to non-transparent materials and liquid. According to the studies on problems above, the technique of ultrasonic measurement on large-volume cubic apparatus has been further developed. As capability of ultrasonic measurement being expanded, ultrasonic velocity of the soft materials and single-crystal materials and liquid could be measured under HTHP. The pressure and temperature of sample cell could be more accurately acquired. For higher precision of ultrasonic measurement, primary pressure calibration would be likely realized.
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/4733
专题	研究生_研究生_学位论文
推荐引用方式 GB/T 7714	王志刚. 六面顶压机加载下高温高压静水压声速测量技术及应用研究[D]. 北京. 中国科学院研究生院,2012.

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