Volume 0,Issue 6,2000 Table of Contents
2000(6).
Abstract:
Titanium carbide particle reinforced tungsten matrix (TiC p/W) composites were fabricated using a hot pressing technique The effects of temperature and TiC p content on the thermophysical properties of the composites have been investigated The results show that as temperature increases, specific heat and coefficient of thermal expansion increase monotonically, thermal diffusivity decreases slightly, and thermal conductivity increases gradually The specific heat and the coefficient of thermal expansion of TiC p/W composites increase with increasing TiC p content, according to the mixture ruler The thermal diffusivity and conductivity of TiC p/W composites, which are sensitive to microstructure, decrease greatly with increasing TiC p content The experimental values of the thermal conductivity are considerably lower than the theoretical ones as result of diffraction from defects such as grain boundary and pores in the thermal conducting particles
Titanium carbide particle reinforced tungsten matrix (TiC p/W) composites were fabricated using a hot pressing technique The effects of temperature and TiC p content on the thermophysical properties of the composites have been investigated The results show that as temperature increases, specific heat and coefficient of thermal expansion increase monotonically, thermal diffusivity decreases slightly, and thermal conductivity increases gradually The specific heat and the coefficient of thermal expansion of TiC p/W composites increase with increasing TiC p content, according to the mixture ruler The thermal diffusivity and conductivity of TiC p/W composites, which are sensitive to microstructure, decrease greatly with increasing TiC p content The experimental values of the thermal conductivity are considerably lower than the theoretical ones as result of diffraction from defects such as grain boundary and pores in the thermal conducting particles
2000(6).
Abstract:
研究了通过 sol- gel工艺在普通玻璃表面制备均匀透明的掺银锐钛矿型 Ti O2 光催化复合薄膜。研究表明 :Ti O2 复合薄膜由 Ti O2 球形颗粒组成 ,其颗粒大小在 5 0 nm～ 10 0 nm;薄膜的厚度每镀一次增加约 0 .0 9μm;薄膜中出现的锐钛矿在 (10 1)面具有一定的择优取向。甲基橙水溶液的光催化降解实验表明 :掺银 Ti O2 复合薄膜的表观降解速率常数明显高于未掺银 Ti O2 薄膜的表观降解速率常数 ,这为进一步提高 Ti O2 薄膜的光催化活性开辟了新的途径。
研究了通过 sol- gel工艺在普通玻璃表面制备均匀透明的掺银锐钛矿型 Ti O2 光催化复合薄膜。研究表明 :Ti O2 复合薄膜由 Ti O2 球形颗粒组成 ,其颗粒大小在 5 0 nm～ 10 0 nm;薄膜的厚度每镀一次增加约 0 .0 9μm;薄膜中出现的锐钛矿在 (10 1)面具有一定的择优取向。甲基橙水溶液的光催化降解实验表明 :掺银 Ti O2 复合薄膜的表观降解速率常数明显高于未掺银 Ti O2 薄膜的表观降解速率常数 ,这为进一步提高 Ti O2 薄膜的光催化活性开辟了新的途径。
2000(6).
Abstract:
在磷酸系晶型控制剂的作用下 ,通过氢氧化钙悬浊液的非均相沉淀法合成了文石型晶须 ,研究了在此方法中晶型控制剂、温度以及初始 p H值等工艺因素对文石生长的影响规律。利用粉末 X射线衍射分析了所合成样品中文石的含量 ,同时用扫描电镜 (SEM)观察了合成晶须的形貌状态。经过实验发现 ,当在氢氧化钙悬浊液中添加磷酸系晶型控制剂后 ,体系具有类似的碳酸化过程 ,但是当采用磷酸或酸性的磷酸盐作为控制剂时 ,作用要优于碱性磷酸盐 ,所获得的样品中文石的含量明显较高。适合于文石生长的温度范围为 2 98K～ 348K,初始酸度值范围为 8.6～ 12 .4。通过研究镁离子与磷酸根离子对文石生长的协同作用后发现 ,镁离子对文石晶体的生长作用明显优于磷酸根 ,当它们同时存在于溶液中时 ,镁离子的作用可以掩盖磷酸根离子的作用。
在磷酸系晶型控制剂的作用下 ,通过氢氧化钙悬浊液的非均相沉淀法合成了文石型晶须 ,研究了在此方法中晶型控制剂、温度以及初始 p H值等工艺因素对文石生长的影响规律。利用粉末 X射线衍射分析了所合成样品中文石的含量 ,同时用扫描电镜 (SEM)观察了合成晶须的形貌状态。经过实验发现 ,当在氢氧化钙悬浊液中添加磷酸系晶型控制剂后 ,体系具有类似的碳酸化过程 ,但是当采用磷酸或酸性的磷酸盐作为控制剂时 ,作用要优于碱性磷酸盐 ,所获得的样品中文石的含量明显较高。适合于文石生长的温度范围为 2 98K～ 348K,初始酸度值范围为 8.6～ 12 .4。通过研究镁离子与磷酸根离子对文石生长的协同作用后发现 ,镁离子对文石晶体的生长作用明显优于磷酸根 ,当它们同时存在于溶液中时 ,镁离子的作用可以掩盖磷酸根离子的作用。
2000(6).
Abstract:
Li 4SiO 4 x Eu 2O 3( x =0 00 to 0 15) ionic conductors were prepared by a Sol Gel method. Structure, shape, and ionic conductivity have been studied using DTA TG, XRD, TEM and AC impedance techniques. The experimental results show that Li 4SiO 4 can be synthesised at low temperatures using the sol gel method, and that its ionic conductivity is higher than that of the sample prepared by solid state reaction. Suitable Eu 2O 3 doping improves ionic conductivity of Li 4SiO 4.
Li 4SiO 4 x Eu 2O 3( x =0 00 to 0 15) ionic conductors were prepared by a Sol Gel method. Structure, shape, and ionic conductivity have been studied using DTA TG, XRD, TEM and AC impedance techniques. The experimental results show that Li 4SiO 4 can be synthesised at low temperatures using the sol gel method, and that its ionic conductivity is higher than that of the sample prepared by solid state reaction. Suitable Eu 2O 3 doping improves ionic conductivity of Li 4SiO 4.
2000(6).
Abstract:
通过保持一定钎焊温度 ,改变钎焊时间得到不同反应层厚度的 Al2 O3/Ag Cu Ti界面。结合扫描电镜 (SEM)和力学试验结果 ,分析了反应层厚度对 Al2 O3/Ag Cu Ti/Ti- 6 Al- 4V接头强度的影响。结果表明 :厚度为 1.5μm时 ,接头强度达到最大值 12 5 MPa;厚度小于 1μm,剪切试样沿反应层和 Al2 O3陶瓷界面断裂 ;大于 3μm,沿反应层断裂。反应层厚度较薄时 ,接头强度取决于界面强度和残余应力的大小 ;反应层厚度较厚时 ,接头强度取决于反应层自身强度和残余应力的大小。
通过保持一定钎焊温度 ,改变钎焊时间得到不同反应层厚度的 Al2 O3/Ag Cu Ti界面。结合扫描电镜 (SEM)和力学试验结果 ,分析了反应层厚度对 Al2 O3/Ag Cu Ti/Ti- 6 Al- 4V接头强度的影响。结果表明 :厚度为 1.5μm时 ,接头强度达到最大值 12 5 MPa;厚度小于 1μm,剪切试样沿反应层和 Al2 O3陶瓷界面断裂 ;大于 3μm,沿反应层断裂。反应层厚度较薄时 ,接头强度取决于界面强度和残余应力的大小 ;反应层厚度较厚时 ,接头强度取决于反应层自身强度和残余应力的大小。
2000(6).
Abstract:
利用 SEM,TEM对 Ti C粒子增强的钛基复合材料的强化方式进行研究 ,得出 :当反应界面厚度控制在 0 .5μm～ 2 μm时 ,界面将起到良好的传递载荷的作用 ,使粒子承载。当粒子的粒度较小 (d P<1μm) ,Orowan强化机制将参与材料强化 ,而当粒子较大时 (d P>1μm) ,阻碍位错滑移。由于两相之间的不均匀变形 ,在界面形成较高的应力集中 ,阻碍形变 ,并可产生形变位错源 ,使基体中位错增殖 ,形成位错胞 ,强化基体。当扩展裂纹遇到 Ti C粒子 ,使扩展路径发生偏转 ,增加裂纹扩展能量 ,提高了材料的强度。
利用 SEM,TEM对 Ti C粒子增强的钛基复合材料的强化方式进行研究 ,得出 :当反应界面厚度控制在 0 .5μm～ 2 μm时 ,界面将起到良好的传递载荷的作用 ,使粒子承载。当粒子的粒度较小 (d P<1μm) ,Orowan强化机制将参与材料强化 ,而当粒子较大时 (d P>1μm) ,阻碍位错滑移。由于两相之间的不均匀变形 ,在界面形成较高的应力集中 ,阻碍形变 ,并可产生形变位错源 ,使基体中位错增殖 ,形成位错胞 ,强化基体。当扩展裂纹遇到 Ti C粒子 ,使扩展路径发生偏转 ,增加裂纹扩展能量 ,提高了材料的强度。
2000(6):361-365.
Abstract:
Laser rapid prototyping based on metallic powders is a new manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The deposition mechanism, deposition system as well as the newest advance in this technology are presented. Some prospects are also predicted.
Laser rapid prototyping based on metallic powders is a new manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The deposition mechanism, deposition system as well as the newest advance in this technology are presented. Some prospects are also predicted.
2000(6):366-369.
Abstract:
The developmental history and application of magnetostrictive materials are introduced. Their characteristics are compared with those of Pb(Zr,Ti)O 3 piezoelectric (PZT) ceramics. The results of some research on ultraprecise micromoving actuators and optical fiber magnetoelastic sensors conducted in our laboratory are presented. Future applications of these materials are also discussed.
The developmental history and application of magnetostrictive materials are introduced. Their characteristics are compared with those of Pb(Zr,Ti)O 3 piezoelectric (PZT) ceramics. The results of some research on ultraprecise micromoving actuators and optical fiber magnetoelastic sensors conducted in our laboratory are presented. Future applications of these materials are also discussed.
2000(6):370-373.
Abstract:
The electric properties, magnetic properties, phase structure and surface conditions of various kinds of austenitic stainless steel fibres are studied, and compared with those of stainless steel bulk. The experimental results may provide a scientific basis for further improving the manufacture technique and properties of austenitic stainless steel fibres.
The electric properties, magnetic properties, phase structure and surface conditions of various kinds of austenitic stainless steel fibres are studied, and compared with those of stainless steel bulk. The experimental results may provide a scientific basis for further improving the manufacture technique and properties of austenitic stainless steel fibres.
2000(6):374-377.
Abstract:
Rare earth ceramics, La 0 67 Ba 0 33 Mn 1- x Fe x O 3( x =0,0 05,0 1), has been prepared. The saturation magnetization and Curie temperature decrease with increasing Fe content in the compounds La 0 67 Ba 0 33 Mn 1- x Fe x O 3,since Fe does not participate in double exchange interaction and the amount of bond Mn 3+ O 2 Mn 4+ decreases. The ferromagnetic interaction decreases with Fe doping in the compounds La 0 67 Ba 0 33 Mn 1 x Fe x O 3. Fe doping also dereases the transition temperature of the metal semiconductor transition peak and increases the resistance of La 0 67 Ba 0 33 Mn 1 x Fe x O 3. The colossal magneloresistance(CMR) effect at low temperatures has been improved for doped La 0 67 Ba 0 33 Mn 1 x Fe x O 3. The magnetoresistance ratio [ R (6T) R (0)]/ R (0) changes from 40% to 60% with increasing Fe content from x=0 to x=0 1 . The results also show that the metal semiconductor transition peak and the negative CMR effect are well described by the Dionne model.
Rare earth ceramics, La 0 67 Ba 0 33 Mn 1- x Fe x O 3( x =0,0 05,0 1), has been prepared. The saturation magnetization and Curie temperature decrease with increasing Fe content in the compounds La 0 67 Ba 0 33 Mn 1- x Fe x O 3,since Fe does not participate in double exchange interaction and the amount of bond Mn 3+ O 2 Mn 4+ decreases. The ferromagnetic interaction decreases with Fe doping in the compounds La 0 67 Ba 0 33 Mn 1 x Fe x O 3. Fe doping also dereases the transition temperature of the metal semiconductor transition peak and increases the resistance of La 0 67 Ba 0 33 Mn 1 x Fe x O 3. The colossal magneloresistance(CMR) effect at low temperatures has been improved for doped La 0 67 Ba 0 33 Mn 1 x Fe x O 3. The magnetoresistance ratio [ R (6T) R (0)]/ R (0) changes from 40% to 60% with increasing Fe content from x=0 to x=0 1 . The results also show that the metal semiconductor transition peak and the negative CMR effect are well described by the Dionne model.
2000(6):382-385.
Abstract:
The mechanism of mechanical activation synthesis has been investigated in the carbothermal reduction of alumina. It was found that the experimental results can not be explained by Ren's mechanism for two phase composites. The crystal grains refining to nanometer size and microstrain producing in mechanical activation are the main reason for mechanical activation to promote carbothermal reduction of alumina.
The mechanism of mechanical activation synthesis has been investigated in the carbothermal reduction of alumina. It was found that the experimental results can not be explained by Ren's mechanism for two phase composites. The crystal grains refining to nanometer size and microstrain producing in mechanical activation are the main reason for mechanical activation to promote carbothermal reduction of alumina.
2000(6):394-397.
Abstract:
The AlN thin films with preferred orientation were deposited on Si(111) substrates using magnetron reactive sputtering. The effect of sputtering power on surface roughness and structure of the AlN thin films has been investigated. The experimental results indicate that as sputtering power increases, deposited rate also increases, but surface roughness and preferred orientation degree of AlN thin films become bad. Therefore, lower sputtering power should be chosen for preparing AlN thin films of good quality.
The AlN thin films with preferred orientation were deposited on Si(111) substrates using magnetron reactive sputtering. The effect of sputtering power on surface roughness and structure of the AlN thin films has been investigated. The experimental results indicate that as sputtering power increases, deposited rate also increases, but surface roughness and preferred orientation degree of AlN thin films become bad. Therefore, lower sputtering power should be chosen for preparing AlN thin films of good quality.
2000(6):403-407.
Abstract:
研究了一种新型高度β合金化的阻燃钛合金Ｔｉ４０的微观组织。研究表明，Ｔｉ４０合金为单相β合金。其铸态组织中存在四叉晶界及晶界周围的白色区域，不超过７８０℃固溶处理，使其晶粒粗大、晶界宽化，晶界仍由许多小晶粒组成；８２０℃固溶发生再结晶，１１００℃固溶发生二次再结晶，大晶粒中出现亚晶；９５０℃锻造，１０５０℃固溶处理后其组织为Ｓｉ－Ｏ化合物和Ｃｒ－Ｏ化合物组成的网状结构。不低于９１０℃固溶时效处理，大晶粒中出现了许多亚晶，使合金的室温拉伸性能得到最佳匹配。
研究了一种新型高度β合金化的阻燃钛合金Ｔｉ４０的微观组织。研究表明，Ｔｉ４０合金为单相β合金。其铸态组织中存在四叉晶界及晶界周围的白色区域，不超过７８０℃固溶处理，使其晶粒粗大、晶界宽化，晶界仍由许多小晶粒组成；８２０℃固溶发生再结晶，１１００℃固溶发生二次再结晶，大晶粒中出现亚晶；９５０℃锻造，１０５０℃固溶处理后其组织为Ｓｉ－Ｏ化合物和Ｃｒ－Ｏ化合物组成的网状结构。不低于９１０℃固溶时效处理，大晶粒中出现了许多亚晶，使合金的室温拉伸性能得到最佳匹配。
2000(6):408-410.
Abstract:
在等温变形条件下，研究了形变热处理对Ｔｉ－１０２３合金显微组织与力学性能的影响。结果表明：形变热处理对Ｔｉ－１０２３合金组织细化及室温强度的提高有一定的作用，但这种作用较小。此作用较小的原因与近β型Ｔｉ－１０２３合金水冷时细针状马氏体α′析出倾向小及等温变形时位错等晶体缺陷密度较低有关。
在等温变形条件下，研究了形变热处理对Ｔｉ－１０２３合金显微组织与力学性能的影响。结果表明：形变热处理对Ｔｉ－１０２３合金组织细化及室温强度的提高有一定的作用，但这种作用较小。此作用较小的原因与近β型Ｔｉ－１０２３合金水冷时细针状马氏体α′析出倾向小及等温变形时位错等晶体缺陷密度较低有关。
2000(6):411-414.
Abstract:
A near net shaped carbon fiber reinforced Al composite was prepared by a new vacuum squeeze casting process. The technology of mixing fibers and fine particles, the choice of binders, as well as the effect of a carbon coating obtained using a sol gel method are studied in this paper. The experimental results show that the fibers in the composite have a moderate volume fraction and a good distribution. The tensile strength and elastic modulus of the composite reach 900MPa and 200GPa respectively.
A near net shaped carbon fiber reinforced Al composite was prepared by a new vacuum squeeze casting process. The technology of mixing fibers and fine particles, the choice of binders, as well as the effect of a carbon coating obtained using a sol gel method are studied in this paper. The experimental results show that the fibers in the composite have a moderate volume fraction and a good distribution. The tensile strength and elastic modulus of the composite reach 900MPa and 200GPa respectively.
2000(6):423-426.
Abstract:
The effect of trace lithium on the anti corrosion ability of industrially pure copper has been studied. The experimental results show that trace lithium can improve the anti corrosion ability of pure copper in saturated NaCl solution, but the ability decreases with increasing lithium content. The improvement in the anti corrosion property results from the effect of lithium on purification, grain size, microstructure and lattice distortion of copper. The corrosion mechanism is oxidization and electric corrosion between copper and impurities.
The effect of trace lithium on the anti corrosion ability of industrially pure copper has been studied. The experimental results show that trace lithium can improve the anti corrosion ability of pure copper in saturated NaCl solution, but the ability decreases with increasing lithium content. The improvement in the anti corrosion property results from the effect of lithium on purification, grain size, microstructure and lattice distortion of copper. The corrosion mechanism is oxidization and electric corrosion between copper and impurities.
2000(6):427-429.
Abstract:
采用金相、ＸＲＤ、ＳＥＭ观察分析了Ｋｏｖａｒ合金（铁镍钴合金）氧化膜的连续性、厚度对封接件的透气率、抗拉强度的影响。结果表明：合金的顶氧化处理能改善玻璃与Ｋｏｖａｒ合金的封接性能，降低渗漏率，提高封接强度；氧化膜的连续性，致密性对封接有重要作用；具有尖晶石型结构的氧化膜对封接有利，且氧化膜最佳增重是３ｇ／ｍ＾２～７ｇ／ｍ＾２。
采用金相、ＸＲＤ、ＳＥＭ观察分析了Ｋｏｖａｒ合金（铁镍钴合金）氧化膜的连续性、厚度对封接件的透气率、抗拉强度的影响。结果表明：合金的顶氧化处理能改善玻璃与Ｋｏｖａｒ合金的封接性能，降低渗漏率，提高封接强度；氧化膜的连续性，致密性对封接有重要作用；具有尖晶石型结构的氧化膜对封接有利，且氧化膜最佳增重是３ｇ／ｍ＾２～７ｇ／ｍ＾２。
2000(6):430-433.
Abstract:
A computer controlled vacuum annealing furnace for Zr and Ti tubing is described using this system. The annealing process parameters can be measured, and optimized.
A computer controlled vacuum annealing furnace for Zr and Ti tubing is described using this system. The annealing process parameters can be measured, and optimized.
