自蔓延高温合成Ti—Ni合金

研究了热爆法和预热燃烧法合成 Ti-Ni 合金的自蔓延高温合成工艺。试验结果表明:低加热速度也能实现 Ti-Ni 的热爆合成;预热温度对燃烧法反应影响很大。探讨了 TiNi、Ti_2Ni、TiNi_3的形成温度,提出了燃烧合成 TiNi 的反应过程模型。大量液相的出现对燃烧反应合成 Ti-Ni 至关重要。     

自蔓延高温合成金属钒的热力学研究

对自蔓延高温合成金属钒的吉布斯自由能、单位热效应及绝热燃烧温度进行热力学计算和分析。结果表明,自蔓延高温合成金属钒能自发进行,且反应剧烈;绝热燃烧温度为3 021K,单位热效应为4 988J/g;高纯V2O5和铝粉的反应在943K左右发生,为液—固反应。     

自蔓延高温合成新工艺

本文试图研究自蔓延高温合成（ＳＨＳ）过程及查明ＳＨＳ过程的优点和特性。     

Ti-W-C体系的自蔓延高温合成与反应机理

研究了Ti-W-C体系自蔓延高温合成(SHS)的燃烧温度和燃烧速度与W含量、Ti粉粒度及预热温度的关系。分析了不同W含量和预热温度时SHS产物的相组成,并对体系的SHS反应机理进行了研究。结果表明:W/(Ti+W)≤ 0.3时,基本能合成单相(W/Ti)C;而预热可促进(W,Ti) C的SHS合成;体系的SHS反应过程中存在两种反应机制,即溶解-析出机制和扩散-固溶机制     

自蔓延高温合成工艺及其应用

自蔓延高温合成工艺制成的材料具有较高的纯度，是新发展的制备高技术材料，金属间化合物和其他新材料的工艺方法。近年来ＳＨＳ法已在某些领域达到工业性生产规模。     

自蔓延高温合成氮化硅的研究

本文在106炉生产规模氮化硅的合成试验中,通过对高压釜内氮气温度与压力的变化计算出在合成过程中耗氮量的变化,计算结果表明,氮化硅燃烧合成的特点属自蔓延高温合成中非稳态合成。其燃烧模式为振荡燃烧及螺旋燃烧。此外,氮气渗透率与高压釜内氮压及氮气渗透阻力有关。     

微波协助自蔓延高温合成技术新进展

对近年来微波协助自蔓延高温合成技术进展进行了简要综述 ,并针对微波协助内部快速加热和选择性介电加热等特性 ,提出了 30多种可能适合微波协助自蔓延高温合成的材料。     

自蔓延高温合成制备TiB2

采用Ｔｉ和Ｂ粉压坯，用电焊机作燃烧合成时的点火装置，利用燃烧合成方法制备ＴｉＢ２。用ＸＲＤ、ＳＥＭ技术对合成产物进行结构、组织分析。结果表明，用燃烧合成法在４５７．０℃～８５６．１℃之间可制备得到ＴｉＢ２。用自蔓延高温合成（ＳＨＳ）制备ＴｉＢ２粉末，其粒度可达１～５μｍ。     

陶瓷和化合物的自蔓延高温合成研究和应用

自蔓延高温合成法是1967年由苏联人提出的,但直到八十年代,一些陶瓷化合物材料成为极重要的结构、切削及各种功能特性材料时,才得到了重视和发展。本文综合介绍了这种方法的基本原理、特征及一些制备技术和应用。     

自蔓延高温合成技术及发展

自蔓延高温合成（ＳＨＳ）是一项很有希望的制备材料的新技术,与传统工艺相比,自蔓延高温合成具有许多优点。对该合成法的历史发展,应用和理论研究作了简要概括,并全面系统地介绍了ＳＨＳ的工艺技术,其中包括与传统技术相结合的ＳＨＳ技术及在ＳＨＳ基础上的新技术。     

自蔓延高温合成多孔陶瓷(Al2O3-TiB2)的研究

本文分析了Al2O3-TiB2体系舢粉粒度、添加剂和成形压力对产物性能的影响，以及燃烧过程、相组成。并测试了样品性能。通过研究，了解到SHS技术制备的多孔陶瓷，其显气孔率与孔径无明显的依赖关系，前者主要取决于生坯密度，而后者取决于原材料Al粉的粒度及添加剂等。同时提出了可控孔隙结构的制备工艺，能够制备出显气孔率为40％～75％、孔径为1-500μm的管状、杯状、圆片状和柱状的多孔陶瓷试样。     

The thermodynamics of the Ni-Co-S ternary system

The thermodynamic properties of the Ni-Co-S ternary system were determined by equilibrating the system with a known sulfur pressure established by using a gas mixture of H₂S/H₂ at 1373, 1473, and 1573 K. The isoactivity contours for Ni and Co were determined by application of the Gibbs-Duhem equation using Schuhmann’s method for ternary systems. For this purpose, a computer program was developed to calculate the activities of nickel and cobalt. The cobalt activity coefficients in dilute solutions of cobalt in the nickel-cobalt-sulfur system were evaluated and found to be 0.33, 0.50, and 0.55 at 1373, 1473, and 1573 K, respectively.     

High-temperature phase relations and thermodynamics in the silver-tin-sulfur system

The SnS activities in liquid Ag₂S-SnS liquid mattes were obtained at 1100 °C and 1200 °C by the dew-point method. Negative deviations were observed, and the liquid matte solutions were modeled by the Wilson equations. Part of the liquid boundaries of the Ag₂S-SnS phase diagram were derived from the model equations, yielding a eutectic temperature of 528 °C at x _SnS=0.38. The phase diagram of the pseudobinary Ag₂S-SnS was also verified experimentally by quenching samples equilibrated in evacuated and sealed silica capsules. Solubility limits of the components at the narrow-terminal solid-solution ranges were determined around the eutectic temperature. Within the Ag-Sn-S ternary system, the boundaries of the immiscibility region, together with the tie-line distributions, were established at 1200 °C. Activities of Ag, Sn, and S along the miscibility gap were calculated by utilizing the bounding binary thermodynamics, phase equilibria, and tie-lines.     

High-temperature phase relations and thermodynamics in the iron-lead-sulfur system

The PbS activities in FeS-PbS liquid mattes were obtained at 1100 °C and 1200 °C by the dew-point method. Negative deviations were observed, and the liquid-matte solutions were modeled by the Krupkowski formalism. The liquid boundaries of the FeS-PbS phase diagram were derived from the model equations yielding a eutectic temperature of 842 °C atX _Pbs = 0.46. A phase diagram of the pseudobinary FeS-PbS was also verified experimentally by quenching samples equilibrated in evacuated and sealed silica capsules. No terminal solid solution ranges could be found. Within the Fe-Pb-S ternary system, the boundaries of the immiscibility region together with the tie-line distributions were established at 1200 °C. Activities of Pb were measured by the dew-point technique along the metal-rich boundary of the miscibility gap. Activities of Fe, Pb, and S, along the miscibility gap were also calculated by utilizing the bounding binary thermodynamics, phase equilibria, and tie-lines.     

High-temperature phase relations and thermodynamics in the iron-titanium-oxygen system

Phase equilibria and thermodynamics in the FeO-TiO₂-Ti₂O₃ ternary system were studied at 1500 °C and 1600 °C. In particular, the liquid slag-phase region and its saturation boundary with respect to metallic iron, titania, and lower titanium oxides was investigated. The liquid slag-phase region extends substantially toward an anosovite (Ti₃O₅) composition, and considerable concentrations of divalent iron coexist with trivalent titanium in the liquid-slag phase. This seems to be a consequence of the complete solid solution between ferrous pseudobrookite (FeTi₂O₅) and anosovite (Ti₃O₅), which exists at subsolidus temperatures. The liquid-slag field is significantly enlarged toward the anosovite composition upon increasing the temperature from 1500 °C to 1600 °C. Activities of the components “FeO” and TiO₂ in the liquid-slag region were determined by Gibbs-Duhem integration of the measured oxygen partial pressures at 1500 °C. The FeO shows moderate negative deviation, while titania shows a slight negative deviation in FeO-rich slags and a positive deviation in high-titania slags. The experimentally measured activity values were modeled using regular and biregular solution models, and good agreement was obtained with the biregular solution model.     

High temperature thermodynamics of the Cr-Cr2N-N2 system

The high-temperature thermodynamic behavior of the Cr-Cr₂N-N₂ system has been investigated in the temperature range 1450 to 1850 K by measuring the equilibrium pressure of nitrogen gas over pure chromium metal and chromium nitride Cr₂N. From the experimental data, the standard free energy and enthalpy of formation of Cr₂N have been determined to be: ΔH° = −104. ± 10 (KJ. mol⁻¹ Cr₂N) ΔG° = −104. + 0.04987 ± 3.8 (KJ. mol⁻¹ Cr₂N)     

Study of the mechanism and regularities of nitriding the complex ferrosilicoaluminum ferroalloy in the SHS mode

The results of an investigation into the mechanism of nitriding the ferrosilicoaluminum complex alloy under isothermal and nonisothermal conditions are presented. It is shown that the nitriding process of ferrosilicoaluminum is complex and multistage. It is established that, when nitriding the ferroalloy, the primary product is AlN; then Si₃N₄ is synthesized and Si₃N₄-based solid solutions are formed. The influence of the main parameters of self-propagating high-temperature synthesis on the velocity and degree of nitriding the ferrosilicoaluminum alloy is investigated. Critical parameters of the combustion process are revealed.     

SHS技术在冶金工业中应用的进展

介绍了ＳＨＳ的特点和这一新技术在冶金工业的应用现状。为扩大其应用范围,提出了若干对策。     

湿法炼锌铅银渣烟化挥发热力学研究

通过热力学计算,得出湿法炼锌铅银渣烟化挥发过程中ZnO、FeO、PbO、Fe2O3还原挥发所需的PCO/PCO2值,并对影响烟化挥发的空气过剩系数α值、渣型等因素进行了初步研究.结果表明:熔炼初期α宜控制在0.8～1.0,还原阶段宜控制在0.6～0.7,此条件能较好地满足烟化挥发过程中热量和还原性气氛的要求.对FeO-SiO2-CaO三元系热力学研究表明,选择CaO 10％～20％、FeO 40％～55％、SiO2 30％～35％的渣型,渣熔化温度小于1 150℃,黏度在0.5～5 Ps·s范围内.