Phase Relationship between 3C- and 6H-Silicon Carbide at High Pressure and High Temperature

The phase relationship between 3C- and 6H-SiC is investigated in the pressure range 2.5–6.5 GPa and the temperature range 400°–2500°C, by analyzing recovered samples, using X-ray diffractometry and Raman-scattering techniques. The phase transition from 3C- to 6H-SiC occurs at 2200°C and 2.5 GPa. In the pressure range >4.5 GPa, 6H-SiC transforms to 3C-SiC at 2500°C, via an intermediate state, as indicated by broadening peaks in the X-ray diffraction profile. Thermodynamically, 3C-SiC appears to be the low-temperature stable form, and the temperature of transition to 6H-SiC, which is stable at high temperature, appears to increase with pressure.     

Fe基合金/石墨系柱状金刚石的高温高压合成与表征

用国产SPD 6×1200型六面顶压机,在10%Fe/90%Fe70Ni30粉末触媒和石墨（Fe–C）体系中,在压力为5.0～5.5 GPa、温度为1 550～1 600 K下合成出柱状金刚石晶体。研究了晶体的形态和生长习性。结果表明：合成的柱状金刚石晶体的颜色呈现绿色,晶体的长度为0.6～0.8 mm,长径比约为2....     

Effects of B2O3 on the Phase Stability of Ba2Ti9O20 Microwave Ceramic

Preparation of dense and phase-pure Ba₂Ti₉O₂₀ is generally difficult using solid-state reaction, since there are several thermodynamically stable compounds in the vicinity of the desired composition and a curvature of Ba₂Ti₉O₂₀ equilibrium phase boundary in the BaO–TiO₂ system at high temperatures. In this study, the effects of B₂O₃ on the densification, microstructural evolution, and phase stability of Ba₂Ti₉O₂₀ were investigated. It was found that the densification of Ba₂Ti₉O₂₀ sintered with B₂O₃ was promoted by the transient liquid phase formed at 840°C. At sintering temperatures higher than 1100°C, the solid-state sintering became dominant because of the evaporation of B₂O₃. With the addition of 5 wt% B₂O₃, the ceramic yielded a pure Ba₂Ti₉O₂₀ phase at sintering temperatures as low as 900°C, without any solid solution additive such as SnO₂ or ZrO₂. The facilities of B₂O₃ addition to the stability of Ba₂Ti₉O₂₀ are apparently due to the eutectic liquid phase which accelerates the migration of reactant species.     

高温高压制备黑色立方氮化硼

利用国产六面顶压机,采用高压合成技术,以温度(1200-1500℃)、压力(5 GPa)、时间(20-60 min)及触媒(MgMg3N2)等为试验影响因素进行了探究,并对实验结果先进行光学显微镜形貌分析,然后再对块体试样进行XRD分析,最后对其机理进行了探究。通过改变实验变量得出最佳合成工艺:在Mg/Mg3N2为1/4、温度为1250℃、压力为5 GPa、MgMg3N2/h BN为1/4,保温时间为40 min的具体工艺下,制备出了产量较高的高性能黑色c BN晶体。     

高温高压往复泵在加氢项目中的应用

加氢项目关键设备加氢进料泵,因工作环境要求非常苛刻,它的选型一直是技术人员难以取舍的难题,文章主要对加氢装置中高温高压泵的选型,目前市场状况、高温高压往复泵结构及使用状况等方面进行了介绍,国内技术同样可以制造出高性能的往复泵,使高温高压往复泵技术又提高了一个阶段,填补了国内市场的空白,此泵可在国内市场上广范推广。     

高温容器液压试验值的分析

本文主要讨论高温容器液压试验压力值的确定同各类材料[σ]/[σ]^t比值的关系。     

压力容器设计中对高温结构的考虑

一些设计人员在设计高温压力容器时,通常采用常规的设计方法,并未对高温结构问题予以特殊的关注。在实际设计中,应对其材料、局部结构、压力容器整体的膨胀量等加以注意。文中对一些高温设备结构设计中的几个问题进行探讨,可供压力容器设计人员参考。     

大型化工厂高压蒸汽减温减压联锁改造

阐述了调解大型化工厂高压蒸汽与中压过热蒸汽的稳定对于化工企业的重要性。修改设计存在的蒸汽调解及联锁逻辑弊端,为蒸汽动力的平稳输送奠定了基础,保证了化工企业的生产连续性,提高了经济效益。     

Properties of Boron Nitride (BxNy) Films Produced by the Spin-Coating Process of Polyborazine

Boron-rich boron nitride (BN) films have been prepared on Si and SiO₂/Si substrates by the vacuum pyrolysis of spin-coated polyborazine films. Physical properties of the prepared films such as film strength, thermal conductivity, and dielectrics were determined. The BN films vacuum-pyrolyzed at 900°C showed residual N–H bonds with a 0.75 N/B ratio, interdiffusion phenomena, and preferred orientation at the interfacial zone. Hardness and the elastic modulus of the film increased to 1.6 GPa and 50 GPa by nanoindentation loading. It had a thermal conductivity of 134 W/(m·K) at 296.5 K, and a dielectric constant in the range of 5–7, with tan ∂ between 0.01 and 0.47, depending on the film thickness.     

高温高压动态腐蚀速率及阴离子浓度影响研究

中东地区伊拉克新投产的H油田地表水资源有限,急需研究注海水工程配套技术,因此海水对注水管柱的腐蚀速率显得至关重要。以H油田注水系统环节涉及的6种挂片(碳合金、35Cr Mo、N80、L80、80ss、90s)为研究对象,以高温高压动态腐蚀仪为技术手段,研究了高温高压及离子浓度变化条件下的动态腐蚀速率情况,研究表明,碳合金、35Cr MO和N80属于尚耐蚀型材料,L80、80ss和90s属于完全耐蚀型材料,从技术经济较大考虑推荐L80和80ss管材。Cl~-、SO_4~(2-)和HCO_3~-浓度对腐蚀速率影响主次顺序为:Cl-HCO_3~-SO_4~(2-)。     

Solid-Solution Ranges of the n= 2 and n= 3 Superconducting Phases in Bi2(SrxCa1 −x)n+1CunOy and the Effect on Tc

The cation solubility limits of the n = 2 and n = 3 superconducting phases in the Bi₂(Sr _x Ca_{1 − x} ) _{n +1}Cu _n O _y system were established along tie lines with compatible phases via electron probe microanalysis on bi- (or poly-) phasic samples prepared at 860°C. Pb additions (15 mol% of the Bi content) were used to facilitate formation of the n = 3 phase. In each case football-shaped volumes in composition space were established as the solubility limits which bordered on the nominal compositions 2212 or 2223 (Bi:Sr:Ca:Cu) with the long axis parallel to the Sr-Ca side of the quaternary (i.e., Sr-to-Ca intersolubility) but also extending toward Bi and Cu. This means that, for the most part, the superconducting phases are alkaline-earth deficient relative to the ideal 2212 and 2223 compositions. The Pb content in the 2223 phase is typically 10% of the Bi content. T _c variations could be correlated with variations in Sr or (Sr + Bi) content and the length of the c -axis parameter.     

高温高压全油基钻井液流变性研究与评价

选用Rheo-Stress 6000型高温高压流变仪,测定不同密度、不同温度（60℃、120℃、150℃、180℃和200℃）和压力梯度下白油全油基钻井液的流变特性。实验结果表明,无论哪种密度的油基钻井液,温度升高都使其表观粘度、剪切应力降低,压力增加都使其增大：150℃的高温下,随着压强的增加,钻井液粘度增幅越来越小,后期趋于平缓,温度和压力同时作用于钻井液流体时,温度占主导作用;在较高的压力和温度下,白油全油基钻井液体系仍有很好的塑性粘度和动切力;此配方白油全油基钻井液在高温高压条件下体系稳定,剪切稀释性好。     

正癸烷高温高压下等压热容测定新方法

针对航空燃料高温高压条件下的等压热容测试,建立了一种新的在线测量装置和测试方法。通过冷、热油对冲混合方式,基于能量守恒原理建立了等压热容的计算公式;基于自制的燃料高温高压流动装置,增加混油和测温部件建立了等压热容测试的实验装置。通过对相关物理量测试不确定度分析,计算得到等压热容的相对扩展不确定度为±3.78%;采用纯水进行标定,验证了该方法测试等压热容的可靠性和精确性。采用航空燃料中的常用组分正十烷,实验测定了在2.1和3.0MPa压力下的等压热容数据,与采用Supertrapp软件的拟合值吻合很好,误差基本在±5%以内。     

高温高压临氢换热器硫化氢腐蚀原因与修复

分析了高温高压临氢换热器硫化氢腐蚀原因,介绍了腐蚀表面现场修复方法,包括腐蚀表面加工、预热、施焊操作与安全防护、焊后热处理及检验等关键工艺。采用ER309LSi不锈钢作为堆焊层,通过合理的焊接工艺,可以减缓温高氢-硫化氢环境下的腐蚀。     

高温高压下气体在水／地层水中的溶解度：实验装置的建立和校核

高温高压下气体在水／地层水中的溶解度实验装置的建立和校核郑大庆高军孙大平郭天民（石油大学油气藏流体高压相态及物性研究室，北京１０２２００）关键词高温高压气体溶解度实验装置１引言近年来在我国陆上和海上地层更深处相继发现了一些储量可观的天然气藏。其中有...     

耐高温丙烯酸酯乳液压敏胶的固化及性能研究

将环氧有机硅固化剂9301以及异氰酸固化剂2102加入到增黏丙烯酸酯乳液中,成功制备出耐高温丙烯酸酯压敏胶。研究压敏胶的固化行为,探讨固化剂的种类和用量对压敏胶粘接性能及耐温性的影响。结果表明:固化剂与复合物发生了交联反应,9301和2102固化体系的适宜固化条件分别为150℃/5min和110℃/3min。随着固化剂用量增加,压敏胶的凝胶率和玻璃化转变温度提高,剥离时由内聚破坏转变为界面破坏,初黏力与剥离强度降低,耐高温性能得到改善。当9301与2102用量为2wt%时,压敏胶的剥离强度分别为11.6N/25mm与10.2N/25mm,可耐180℃高温。     

电子元件定位用耐高温压敏胶带研制

本文介绍了以具有双官能团的氯化基胶ＣⅡＲ为主要原料,研制耐１７０℃高温压敏胶的合成工艺和涂胶制带工艺。     

低温撞击破碎高能发射药结构特征与高压燃烧性能研究

在-40℃下,通过落锤撞击制备了不同破碎程度的DAGR125和NR11发射药,利用染料吸附量表征了发射药的破碎程度,结合密闭高压爆发器实验,分析了破碎发射药结构特征与高压燃烧特征的关系。结果表明,随着小颗粒破碎发射药的增加,动态活度变化率在燃烧初始阶段发生转折。当破碎程度较小时,初始动态活度、染料吸附量均可衡量发射药初始燃面和破碎程度;当破碎程度较大时,利用传统方法获取的初始动态活度明显小于实际值,不适合用来表征初始燃面,而染料吸附量法更为准确。初始动态活度变化规律显示,当落锤高度大于60cm时,发射药药粒的破碎程度快速增加;动态活度变化规律显示,落锤高度分别大于23.0cm和23.1cm时,DAGR125和NR11破碎发射药整体燃烧过程由增面性转变为减面性。     

Phase Relations and Volume Changes of Hafnia under High Pressure and High Temperature

Using multi-anvil high-pressure devices and synchrotron radiation, X-ray in situ observations of HfO₂ under high pressure and high temperature have been performed to investigate its phase relations and compression behavior. An orthorhombic phase (orthoI) is stable from 4 to 14.5 GPa below 1250°–1400°C and transforms to a tetragonal phase, which is one of the high-temperature forms of HfO₂, above these temperatures. Another orthorhombic phase (orthoII) with a cotunnite-type structure appears above 14.5 GPa. OrthoII is stable up to 1800°C at 21 GPa. OrthoII is quenchable to ambient conditions. The orthoI-to-orthoII transition is accompanied by ∼8 vol% decrease. The bulk moduli of orthoI and orthoII at room temperature are 220 and 312 GPa, respectively. This low compressibility of orthoII indicates that it is a potential candidate for very hard materials.