近化学计量比钽酸锂晶体生长及表征

用高纯H2TaF7溶液经过过氧化反应、沉淀等一系列反应制得的钽酸盐化合物晶体作为初始原料,掺入一定剂量的K2O助熔剂,用提拉法生长近化学剂量比的钽酸锂晶体,结果得到尺寸为φ45 mm×45 mm的SLT晶体,并对该晶体的性能进行了表征.结果表明,尺寸为φ45 mm×45 mm的SLT晶体畴结构为完全六边形,本征缺陷比CLT晶体均明显减少;吸收边相对于CLT晶体发生了蓝移,蓝移5.8 nm;经外吸收变弱,经工外透过率为78%;抗光损伤能提高,达到108 W/cm2.是性能优良的光学材料,使介电体超晶格高频超声原件和全固态白光激光器的研制成为现实.     

金属铪的制备及应用

1金属铪的性质 自然界中没有单独的铪矿物存在,铪总是与锆共生.锆矿物中共生的铪含量,一般仅为锆的1%～2%,只有个别矿物铪含量可达5%.铪的制备工艺复杂且量又少,使其成为名符其实的稀有金属.铪属高熔点难熔金属,原子量178.49,熔点2 222℃(±30℃).金属铪具有优良的加工性能,可以锻压、拉丝.但最为重要的是铪的核性能.     

废硫酸回收用钽管的加工研究

研究了废硫酸回收用钽管的加工工艺.通过改进挤压管坯镗内孔的工艺,实现了挤压管坯不中断,用较长的挤压管坯生产Φ25×0.9×11 000 mm 的长钽管,减少了管材切头尾的长度,提高了管材成品率.在确定成品管前一道次管坯的尺寸时,要综合考虑LD30轧机最大装料长度、钽材的变形程度和减径量与减壁量的比值.用本工艺所制备的钽管已用于废硫酸回收的钽蒸发器的制造,获得良好的应用效果.     

Ta2O5掺杂玻璃/钙长石复合绝缘材料性能的研究

采用传统烧结技术制备出稀土氧化钽掺杂玻璃/钙长石复合材料,并进行了XRD、SEM和性能测试,分析了稀土氧化钽对烧结温度及材料性能的影响.结果表明,添加适量的氧化钽有利于改善材料的力学性能,降低烧结温度,但对材料的介电性能有一定影响.当氧化钽最佳的掺杂量为2%(质量分数)时,所制备的复合材料具有高的相对密度(≥97.5%)、低的烧结温度(850～900℃)、低的介质损耗(0.35%～0.37%)、低的膨胀系数((3.40～3.41)×10-6/℃)和较高的抗折强度(128.6～137.4MPa).     

终轧加工率对钼及钼镧合金板材组织及性能的影响

以粉末冶金方法生产的25 mm×280 mm×320 mm纯钼及钼镧合金板坯为实验原料,研究了不同的热轧终轧加工率对钼及钼镧合金板显微组织及力学性能的影响.结果表明,将纯钼及钼镧合金板热轧终轧加工率控制在50%以上,轧后纯钼板材的显微组织为细化的纤维流线组织,纵、横向的Rm分别为795,885 MPa,A5分别达到27%,21%,其后续的温轧加工不开裂;而钼镧合金板材不论是显微组织,还是力学性能均好于纯钼.进一步的生产实践证明,将钼及钼镧合金板的热轧终轧加工率控制在50%以上,其强度、塑性和硬度匹配良好,弯曲性能和后序的温轧加工性能明显提高.     

稀有金属王国中的姊妹花--锆和铪

在神奇的稀有金属王国里,一些金属元素由于镧系收缩效应,电子结构和物理化学性质相似,具有"元素对"的矿物特征,常常成对出现在矿物中,如钽和铌、钨和钼.锆和铪就是这些元素对中的一对挛生姊妹,在自然界中共生,一般锆矿物中铪只占锆铪总质量的1%～2%,也有少量含铪高的矿物可达到5%以上.     

船用Ti-322合金超大规格环材制备技术研究

研究了船用Ti-322钛合金(名义成分Ti-3AL-2Mo-2Zr)超大规格环材制备工艺.首先进行了Gr41:1模拟件和Ti-322小型环件的试制.用摸索的锻造-辗轧联合生产工艺以及设计的工模具制备出了φ2 200 mm/φ1 700 mm×300 mm Ti-322合金环件.对该环件进行850℃,1 h,AC整体热处理,可使其组织和性能均匀,满足用户的使用要求.     

大塑性变形钨合金的断裂韧性研究

钨及钨合金因熔点高、蒸气压低、热传导率高、耐蚀性及热冲击性良好而使其在高温环境下广泛应用.但形状复杂的零部件加工(如车削等)较困难.大的塑性变形不仅可使材料的拉伸强度升高、硬度增大,而且还可使其韧性提高.高压扭转是一种常用的获得细晶的大塑性变形法.高压扭转时,将φ6 mm×0.8 mm薄片状试样插入到2个互相挤压的砧台之间.因钨的屈服应力高达705～815 MPa,砧台采用较硬的Co-93WC制作.高压扭转变形温度恒定为400℃,试样经受近10 GPa的流体静压力.奥地利研究人员用此方法对纯钨、氧化镧弥散强化的钨合金(WL10)和掺钾的钨合金(WVM)进行高压扭转变形,随后进行室温断裂韧性试验,宽约100 μm、深约15 μm的预制裂纹是采用聚焦离子束切割的,预计缺口半径小于20 nm.3种钨合金的加工工艺分别为:φ23 mm的纯钨烧结棒轧制成φ9 mm的棒材;φ48 mm的WVM烧结棒先锻造至φ23 mm,随后轧制成φ14mm棒材;φ48 mm的WL10烧结棒也轧制成φ9 mm的棒材.     

眼镜架用Ti-22V-4Al合金丝制备工艺研究

Ti-422(Ti-22V-4A1)合金具有优越的综合性能,特别具有很好的冷加工成形性,因此,用于制作高端眼镜架极具潜力.为了获得规模化生产Ti-422合金眼镜丝材的最佳工艺,对该合金冷加工丝材的变形程度和热处理工艺同力学性能和组织结构的关系进行了研究.结果得出,采用φ10 mm热轧坯料,辊模拉拨到φ5.0mm,退火后按55%～70%变形再辊模拉伸制得不同直径的丝材料,经780℃,30 min退火处理,其组织均匀,延伸率达20%以上.然后经520℃,4 h时效处理,维氏硬度达到2800 MPa,完全达到眼镜架用丝材对材料硬度2700 MPa＜Hv＜3000 MPa的技术要求.     

金属铪的应用

1金属铪的性质 自然界中没有单独的铪矿物存在,铪总是与锆共生.锆矿物中共生的铪一般仅为锆的1%～2%,只有个别锆矿物中铪的含量可达5%.铪在自然界中不仅储量少,而且制备工艺复杂,使其成为名副其实的稀有金属.铪属高熔点难熔金属,熔点为2 222℃(±30℃).     

热交换器的分类及优缺点分析

热交换器是将不同温度介质之间的热量通过热传导的形式,由高温介质传递给低温介质,使介质达到生产所需温度的工艺设备,也可作为一种节能设备使用.通过对不同热交换器的结构分析,总结不同热交换器的优缺点、适用环境,为生产工艺设计人员及设备制造单位在选择可降低能耗、提高效率的设备上提供参考.     

聚苯胺及其复合物的制备和结构及形貌分析

通过化学氧化法分别制备盐酸,盐酸和十二烷基苯磺酸,碳纳米管(MWNTs-COOH)掺杂的聚苯胺,利用红外光谱,紫外光谱,扫描电子显微镜和透射电子显微镜对所制备聚苯胺的结构和形貌进行分析。分析不同掺杂物对聚苯胺的结构和形貌的影响;同时研究了超声波作用对聚苯胺形貌以及聚苯胺包裹MWNTs-COOH情况的影响。     

Modelling and computation of curing and damage of thermosets

The curing of thermosets is a complex process involving the transition from a fluid into a (visco-) elastic solid. This phase transition comes along with an increase in stiffness and a volume shrinkage of the polymer. The latter may lead to severe residual strains and stresses, which in turn can cause damage in the final, usually quasi-brittle material. In this contribution a constitutive model is developed which takes into account the curing of a thermosetting material together with the process-induced damage as resulting from curing shrinkage. The curing of the material is governed by a phenomenological hypoelastic constitutive equation which includes temporal evolutions for stiffness and volume shrinkage. Thermal and viscous effects are neglected in the present study. An isotropic gradient-enhanced damage model is adapted to describe the damage evolution. The curing-damage model is implemented into a finite element code and numerical examples for thermosetting materials demonstrate that the proposed model is capable to predict cure-induced damage in thermosets.     

Thermodynamic similarity and prediction of the properties and characteristics of substances and processes

Principles of the theory of thermodynamic similarity are considered in application to all aggregate states of a substance, including phase transitions, and to the change in dissipative structures in open systems.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 53, No. 5, pp. 709–716, November, 1987.     

Mechanisms of Corosion and Oxidation of Metals and Alloys

Selected topics in field of the study of the mechanisms of corrosion and of oxidation of metals or alloys are presented. The first part reports a new model for the mechanism of the breakaway oxidation of ferritic stainless steels in water vapour. The second part is devoted to the physico‐chemical aspects of oxidation and presents experimental methods useful in the kinetic modelling applied to two alloys, the zircalloy‐4 and an AlMg5 % in the liquid state. In the third part the physical and numerical modelling of the stress corrosion cracking behaviour in face‐centered cubic (fcc) alloys is detailed, which enables the study of the influence of macroscopic parameters (such as the temperature or hydrogen activity) on the fracture process.     

碳化硼陶瓷增韧补强和致密化研究现状及其展望

碳化硼陶瓷具有极高的硬度,然而其低韧性、低抗弯强度、难以致密化限制了它的广泛应用.已有一些研究集中于碳化硼陶瓷增韧补强和致密化,对这一方面国内外研究进展进行了归纳与评述,阐明各种增韧补强和致密化方法的优缺点,提出碳化硼陶瓷增韧补强和致密化研究值得发展的一些方向.     

Measurement and analysis of elastic and anelastic properties of alumina and silicon carbide

Measurements of dynamic Young's modulus, E, and damping as a function of temperature, T, were made for alumina and silicon carbide. The Young's modulus data were compared with some from the literature, and analysed in terms of a theoretical framework relating the Debye temperature, θD, with the elastic constants. For both materials this analysis yielded a ratio T₀/θ_D which was near 0.4, where T₀ is an empirical fitting constant for the plot of (E(0)−E)/T versus 1/T (E(0) is the value of E at 0 K). The analysis of the damping data in terms of an Arrhenius type dependence led to effective activation energies near kT, where k is Boltzmann's constant. This revised version was published online in November 2006 with corrections to the Cover Date.     

Preparation and characterization of phosphate and arsenate apatites of strontium and their solid solutions

Samples of phosphate and arsenate apatites of strontium and six of their solid solutions, spread over the entire compositional range, were prepared by a wet method. They were characterized by chemical, X-ray, electron microscopic and infrared analyses. The validity of Vegard's law established the homogeneity of the solid solutions.     

检定和校准证书的异同与应用

本文介绍了检定和校准以及证书的两点相同、五点不同之处,说明了对检定证书和校准证书的正确应用。