Volume 33,Issue 10,2004 Table of Contents
2004, 33(10):1009-1012.
Abstract:
介绍了Mo，Ta，W药型罩材料的制备、材料的力学性能及材料的弹道试验。结果表明，Mo，Ta，W，贫铀合金的侵彻性能均较传统Cu药型罩材料有很大的提高，完全可替代Cu材并满足现代武器发展的要求。同时，还提出了难熔金属药型罩材料的研发方向。
介绍了Mo，Ta，W药型罩材料的制备、材料的力学性能及材料的弹道试验。结果表明，Mo，Ta，W，贫铀合金的侵彻性能均较传统Cu药型罩材料有很大的提高，完全可替代Cu材并满足现代武器发展的要求。同时，还提出了难熔金属药型罩材料的研发方向。
2004, 33(10):1013-1017.
Abstract:
采用粉末冶金方法制备多孔钛样品，孔隙率约为40％，最大孔径为240μm。经过NaOH溶液、热处理后，多孔钛再在Na2HPO4溶液和饱和Ca(OH)2溶液中分别浸泡进行预钙化处理。未经预钙化处理的样品在SBF中浸泡，形成表面磷灰石涂层约需28d的时间。经过预钙化的样品在SBF中浸泡只需4d，这说明预钙化过程大大提高了多孔钛的生物活性。其作用机理为：预钙化过程中样品表面的钛酸钠水解，形成带负电的Ti-OH基团，使Ca^2 离子吸附到表面。在SBF中浸泡时，表面附近在短时间内达到钙一磷过饱和。且Ca^2 离子增大表面附近的DH值，Ca^2 离子和PO4^3-离子、OH^-离子的活度积增大，刺激了磷灰石成核并形成涂层。除碱热处理并预钙化的样品外，其余样品表面磷灰石的Ca／P原子比均小于人体自然骨的Ca／P原子比。涂层的结晶细小而薄，不破坏多孔钛的孔隙结构。
采用粉末冶金方法制备多孔钛样品，孔隙率约为40％，最大孔径为240μm。经过NaOH溶液、热处理后，多孔钛再在Na2HPO4溶液和饱和Ca(OH)2溶液中分别浸泡进行预钙化处理。未经预钙化处理的样品在SBF中浸泡，形成表面磷灰石涂层约需28d的时间。经过预钙化的样品在SBF中浸泡只需4d，这说明预钙化过程大大提高了多孔钛的生物活性。其作用机理为：预钙化过程中样品表面的钛酸钠水解，形成带负电的Ti-OH基团，使Ca^2 离子吸附到表面。在SBF中浸泡时，表面附近在短时间内达到钙一磷过饱和。且Ca^2 离子增大表面附近的DH值，Ca^2 离子和PO4^3-离子、OH^-离子的活度积增大，刺激了磷灰石成核并形成涂层。除碱热处理并预钙化的样品外，其余样品表面磷灰石的Ca／P原子比均小于人体自然骨的Ca／P原子比。涂层的结晶细小而薄，不破坏多孔钛的孔隙结构。
2004, 33(10):1018-1022.
Abstract:
Osteoblast differentiation of rabbit bone marrow cells on apatite-coated titanium by alkali-heat treatment was investigated in present paper. Titanium was subjected to alkali-heat treatment and soaked in acellular simulated body fluid to prepare surface apatite layer. Cell behavior and alkaline phosphatase activity and osteocalcin on apatite-coated titanium were compared with those on commercially pure titanium in vitro. The results show that initial cell adhesion on apatite-coated titanium is higher than that on pure titanium while cell growth rates at a late stage are not significantly different for both groups. Early and later osteoblast differentiation marks, alkaline phosphatase activity and osteocalcin, on apatite-coated titanium are higher than those on pure titanium. Apatite-coated titanium by alkali-heat treatment can increase osteoblast adhesion and displays a higher differentiation capacity for osteoblasts differentiation than that for commercially pure titanium.
Osteoblast differentiation of rabbit bone marrow cells on apatite-coated titanium by alkali-heat treatment was investigated in present paper. Titanium was subjected to alkali-heat treatment and soaked in acellular simulated body fluid to prepare surface apatite layer. Cell behavior and alkaline phosphatase activity and osteocalcin on apatite-coated titanium were compared with those on commercially pure titanium in vitro. The results show that initial cell adhesion on apatite-coated titanium is higher than that on pure titanium while cell growth rates at a late stage are not significantly different for both groups. Early and later osteoblast differentiation marks, alkaline phosphatase activity and osteocalcin, on apatite-coated titanium are higher than those on pure titanium. Apatite-coated titanium by alkali-heat treatment can increase osteoblast adhesion and displays a higher differentiation capacity for osteoblasts differentiation than that for commercially pure titanium.
2004, 33(10):1023-1028.
Abstract:
Polycrystalline samples La2/3Ca1/3MnO3 (LCMO), La2/3(Ca0.5Ba0.5)1/3MnO3 (LCBMO), La2/3Ba1/3MnO3 (LBMO), La2/3(Sr0.5Ba0.5)1/3MnO3 (LSBMO) and La2/3Sr1/3MnO3 (LSMO) have been prepared by a solid state reaction method. We have observed the temperature dependences of the electric resistivity and magnetoresistance from 77 K up to 800 K. Experimental results indicate that the presence of grain boundaries in the colossal magnetoresistance (CMR) materials prepared by the mechanical alloyed method leads to a large magnetoresistance effect at low temperature, and there exists a pronounced metal-semiconductor transition around TC. According to the models of spin-polarized electron tunneling and percolation, the magnetoresistance as a function of temperature has been explained well. The temperature dependence of resistivity at high temperature is well fit by nonadiabatic small polaron hopping model for LCBMO and LSBMO samples, and their activation energies are obtained. Also it has been found that annealing processing affects the resistivity significantly.
Polycrystalline samples La2/3Ca1/3MnO3 (LCMO), La2/3(Ca0.5Ba0.5)1/3MnO3 (LCBMO), La2/3Ba1/3MnO3 (LBMO), La2/3(Sr0.5Ba0.5)1/3MnO3 (LSBMO) and La2/3Sr1/3MnO3 (LSMO) have been prepared by a solid state reaction method. We have observed the temperature dependences of the electric resistivity and magnetoresistance from 77 K up to 800 K. Experimental results indicate that the presence of grain boundaries in the colossal magnetoresistance (CMR) materials prepared by the mechanical alloyed method leads to a large magnetoresistance effect at low temperature, and there exists a pronounced metal-semiconductor transition around TC. According to the models of spin-polarized electron tunneling and percolation, the magnetoresistance as a function of temperature has been explained well. The temperature dependence of resistivity at high temperature is well fit by nonadiabatic small polaron hopping model for LCBMO and LSBMO samples, and their activation energies are obtained. Also it has been found that annealing processing affects the resistivity significantly.
2004, 33(10):1029-1032.
Abstract:
为深入研究激光熔覆反应合成TiCp／Al复合材料过程，数值计算该过程的温度场和流场时需将所发生的化学反应热纳入计算。因此本文采用在试样扫描过程中突然停止激光发射的办法，得到反应过程中不同阶段所形成的组织，进而判断出各阶段所发生的反应；利用差热分析法(DTA)和热力学计算法确定反应热焓值。研究表明：激光熔覆条件下Al-Ti-C粉料层中合成反应的过程为：先发生3Al Ti→Al3Ti反应，再发生Al3Ti C→TiC Al反应。3Al Ti→Al3Ti的反应热为146．63kJ／mol，Al3Ti C→TiC Al的反应热为38．60kJ／mol。该反应热焓值可用于温度场和流场的数值模拟计算。
为深入研究激光熔覆反应合成TiCp／Al复合材料过程，数值计算该过程的温度场和流场时需将所发生的化学反应热纳入计算。因此本文采用在试样扫描过程中突然停止激光发射的办法，得到反应过程中不同阶段所形成的组织，进而判断出各阶段所发生的反应；利用差热分析法(DTA)和热力学计算法确定反应热焓值。研究表明：激光熔覆条件下Al-Ti-C粉料层中合成反应的过程为：先发生3Al Ti→Al3Ti反应，再发生Al3Ti C→TiC Al反应。3Al Ti→Al3Ti的反应热为146．63kJ／mol，Al3Ti C→TiC Al的反应热为38．60kJ／mol。该反应热焓值可用于温度场和流场的数值模拟计算。
2004, 33(10):1033-1036.
Abstract:
The SmCo/Cr films have been prepared with the help of DC magnetron sputtering method. The structure of Cr underlayer depended on several sputtering factors, and directly influenced the coercivity of SmCo/Cr films. The orthogonal design of experiments and mathematical statistical method are considered as the effective methods to optimize sputtering condition of Cr underlayer for high coercivity of SmCo/Cr films. Using the orthogonal design method, the effects of the four factors, such as, the target-substrate distance, the DC power, the sputtering pressure and the sputtering time were simultaneously investigated by only 9 experiments. The optimal condition of Cr underlayer was obtained, that is 4 cm in T-S distace, 50 W in DC power, 0.5 Pa in sputtering pressure, 9 min in sputtering time. The target-substrate distance, the DC power and the sputtering pressure are very important factors for coercivity, on the other hand, the effect of sputtering time is not obvious. It can be proved that our orthogonal design of experiment is of 95% confidence.
The SmCo/Cr films have been prepared with the help of DC magnetron sputtering method. The structure of Cr underlayer depended on several sputtering factors, and directly influenced the coercivity of SmCo/Cr films. The orthogonal design of experiments and mathematical statistical method are considered as the effective methods to optimize sputtering condition of Cr underlayer for high coercivity of SmCo/Cr films. Using the orthogonal design method, the effects of the four factors, such as, the target-substrate distance, the DC power, the sputtering pressure and the sputtering time were simultaneously investigated by only 9 experiments. The optimal condition of Cr underlayer was obtained, that is 4 cm in T-S distace, 50 W in DC power, 0.5 Pa in sputtering pressure, 9 min in sputtering time. The target-substrate distance, the DC power and the sputtering pressure are very important factors for coercivity, on the other hand, the effect of sputtering time is not obvious. It can be proved that our orthogonal design of experiment is of 95% confidence.
2004, 33(10):1037-1040.
Abstract:
The isothermal CVI (chemical vapor infiltration) process of carbon/carbon composites is controlled by many factors and its efficiency is very low. Manufacturing of C/C composites with isothermal CVI processes is costly and thus limits commercial applications of C/C composites. Based on the fuzzy neural network (FNN) technique and genetic algorithm, a predicting system for isothermal CVI process was proposed and established. The simulation results of FEM called virtual samples were selected as the network's training samples. Based on the FNN system, the influences of main infiltration parameters, such as infiltration temperature, precursor gas flow ratio and rate, had been studied; and they are good instructions for the design and optimization of CVI process. Using this FNN system, we expect that we can reduce the time of development and densification, thus reducing manufacturing cost.
The isothermal CVI (chemical vapor infiltration) process of carbon/carbon composites is controlled by many factors and its efficiency is very low. Manufacturing of C/C composites with isothermal CVI processes is costly and thus limits commercial applications of C/C composites. Based on the fuzzy neural network (FNN) technique and genetic algorithm, a predicting system for isothermal CVI process was proposed and established. The simulation results of FEM called virtual samples were selected as the network's training samples. Based on the FNN system, the influences of main infiltration parameters, such as infiltration temperature, precursor gas flow ratio and rate, had been studied; and they are good instructions for the design and optimization of CVI process. Using this FNN system, we expect that we can reduce the time of development and densification, thus reducing manufacturing cost.
2004, 33(10):1041-1044.
Abstract:
An artificial neural network (ANN) model is proposed to predict mechanical properties of Ti-10V-2Fe-3Al titanium alloys. The input parameters of the neural network (NN) model are deformation temperature, degree of reduction, cooling rate, solution temperature and aging temperature. The outputs of the NN model are five most important mechanical properties namely ultimate tensile strength, tensile yield strength, elongation, reduction of area, and fracture toughness. Extensive experiments for correlating forging technology to mechanical properties were conducted in Ti-10V-2Fe-3Al alloy to train the NN. Compared to the traditional regression method, the ANN model has a better compatibility and adaptability. The model can be used for the prediction of properties of Ti-10V-2Fe-3Al alloy as functions of processing parameters and heat treatment cycle. It can also be used for the optimization of the processing and heat treatment parameters.
An artificial neural network (ANN) model is proposed to predict mechanical properties of Ti-10V-2Fe-3Al titanium alloys. The input parameters of the neural network (NN) model are deformation temperature, degree of reduction, cooling rate, solution temperature and aging temperature. The outputs of the NN model are five most important mechanical properties namely ultimate tensile strength, tensile yield strength, elongation, reduction of area, and fracture toughness. Extensive experiments for correlating forging technology to mechanical properties were conducted in Ti-10V-2Fe-3Al alloy to train the NN. Compared to the traditional regression method, the ANN model has a better compatibility and adaptability. The model can be used for the prediction of properties of Ti-10V-2Fe-3Al alloy as functions of processing parameters and heat treatment cycle. It can also be used for the optimization of the processing and heat treatment parameters.
2004, 33(10):1045-1048.
Abstract:
W6.56Ni2.28Fe tungsten heavy alloy from the elemental powders of W, Ni and Fe was mechanically alloyed(MA). Phase was defined by XRD. Microstructure was observed by TEM (JEM-2000 type). Phase evaluation, grain size and lattice distortion of these powders were determined and discussed. And nano-crystalline supersaturated solid solutions and amorphous were prepared by MA. A thermodynamic model was developed based on Miedema semi-experimental theory to calculate the driving force for phase evolution. The thermodynamic analysis showed that there is no chemical driving force to form amorphous alloys. The model of multilayer amorphization during MA was applied to illustrate the feasibility of amorphization of powder with neither ?Hmix << 0 nor DB >DA
W6.56Ni2.28Fe tungsten heavy alloy from the elemental powders of W, Ni and Fe was mechanically alloyed(MA). Phase was defined by XRD. Microstructure was observed by TEM (JEM-2000 type). Phase evaluation, grain size and lattice distortion of these powders were determined and discussed. And nano-crystalline supersaturated solid solutions and amorphous were prepared by MA. A thermodynamic model was developed based on Miedema semi-experimental theory to calculate the driving force for phase evolution. The thermodynamic analysis showed that there is no chemical driving force to form amorphous alloys. The model of multilayer amorphization during MA was applied to illustrate the feasibility of amorphization of powder with neither ?Hmix << 0 nor DB >DA
2004, 33(10):1049-1051.
Abstract:
含锶羟基磷灰石的骨缺损修复效果优于羟基磷灰石。采用湿法合成含锶羟基磷灰石和羟基磷灰石，分别在300℃，600℃，900℃热处理。用Rigaku D／max-3C型X射线衍射仪(XRD)，PE1760．X傅氏红外光谱仪(IR）和X射线散射能谱(EDX)分析粉样和片样的成分，用S-2700扫描电镜(SEM)观察形貌。结果表明：锶使羟基磷灰石的晶面间距变大，热稳定性变差，900℃热处理分解出β-Ca3(PO4)2和CaO2含锶羟基磷灰石的OH^-红外吸收峰弱于羟基磷灰石，但两者的Off和PO4^3-峰位置接近；含锶羟基磷灰石在模拟体液中的溶解．再结晶过程强于羟基磷灰石。
含锶羟基磷灰石的骨缺损修复效果优于羟基磷灰石。采用湿法合成含锶羟基磷灰石和羟基磷灰石，分别在300℃，600℃，900℃热处理。用Rigaku D／max-3C型X射线衍射仪(XRD)，PE1760．X傅氏红外光谱仪(IR）和X射线散射能谱(EDX)分析粉样和片样的成分，用S-2700扫描电镜(SEM)观察形貌。结果表明：锶使羟基磷灰石的晶面间距变大，热稳定性变差，900℃热处理分解出β-Ca3(PO4)2和CaO2含锶羟基磷灰石的OH^-红外吸收峰弱于羟基磷灰石，但两者的Off和PO4^3-峰位置接近；含锶羟基磷灰石在模拟体液中的溶解．再结晶过程强于羟基磷灰石。
11 Effect of Thermo-Mechanical Training on Characterization of DSC Curves of TiNiCu Shape Memory Alloys
2004, 33(10):1052-1055.
Abstract:
Transformation characters of two kinds of TiNiCu two-way shape memory effect (TWSME) spring during excension and contraction training were investigated by DSC measurement during thermo-mechanical training. One of the TWSME spring could extend upon heating and contract upon cooling, the other could contract upon heating and extend upon cooling. The results showed that before training the profile of endothermic peaks were composed of several small peaks. With training the amount of the small peaks decreased. After the stabilized TWSME induced into the TiNiCu alloy, there was only one sharp peak appear. This can attribute to the dislocations structures creates an anisotropic stress field, which guides the orientation of martensite variants very similar. And the dislocations also leads to the decrease of As and Af.
Transformation characters of two kinds of TiNiCu two-way shape memory effect (TWSME) spring during excension and contraction training were investigated by DSC measurement during thermo-mechanical training. One of the TWSME spring could extend upon heating and contract upon cooling, the other could contract upon heating and extend upon cooling. The results showed that before training the profile of endothermic peaks were composed of several small peaks. With training the amount of the small peaks decreased. After the stabilized TWSME induced into the TiNiCu alloy, there was only one sharp peak appear. This can attribute to the dislocations structures creates an anisotropic stress field, which guides the orientation of martensite variants very similar. And the dislocations also leads to the decrease of As and Af.
2004, 33(10):1056-1060.
Abstract:
提出了粉末注射成形冷凝蒸气脱脂新方法，介绍了其工作原理，考查了脱脂温度、时间对粘结剂脱除率的影响。根据Fick第二定律建立了粉末注射成形平板试样、球形试样和圆棒试样冷凝蒸气脱脂过程的数学模型，并给出了该模型的1种图形解法。实验结果表明：该方法脱脂效率高，脱脂坯强度大。利用所建立的机理模型和图形解法可以对简单规则形状成形坯的脱脂过程进行预测，预测结果与实验结果很好的吻合。
提出了粉末注射成形冷凝蒸气脱脂新方法，介绍了其工作原理，考查了脱脂温度、时间对粘结剂脱除率的影响。根据Fick第二定律建立了粉末注射成形平板试样、球形试样和圆棒试样冷凝蒸气脱脂过程的数学模型，并给出了该模型的1种图形解法。实验结果表明：该方法脱脂效率高，脱脂坯强度大。利用所建立的机理模型和图形解法可以对简单规则形状成形坯的脱脂过程进行预测，预测结果与实验结果很好的吻合。
2004, 33(10):1061-1064.
Abstract:
热处理温度显著影响Ni3Al(Zr)合金的显微组织和室温力学性能。本实验采用SEM，TEM，AES等手段对轧制处理后的试样进行了研究。随着热处理温度升高，再结晶体积百分数增加，再结晶晶粒尺寸增大，室温拉伸强度降低。但室温拉伸塑性随热处理温度升高而增加，在850℃热处理时达到最大值，然后随热处理温度升高而显著降低。俄歇能谱(AES)研究表明Zr在850℃热处理时的晶界偏聚量明显高于1100℃热处理时的偏聚量，说明Zr在室温的塑化作用与其在晶界的分布有关。
热处理温度显著影响Ni3Al(Zr)合金的显微组织和室温力学性能。本实验采用SEM，TEM，AES等手段对轧制处理后的试样进行了研究。随着热处理温度升高，再结晶体积百分数增加，再结晶晶粒尺寸增大，室温拉伸强度降低。但室温拉伸塑性随热处理温度升高而增加，在850℃热处理时达到最大值，然后随热处理温度升高而显著降低。俄歇能谱(AES)研究表明Zr在850℃热处理时的晶界偏聚量明显高于1100℃热处理时的偏聚量，说明Zr在室温的塑化作用与其在晶界的分布有关。
2004, 33(10):1065-1068.
Abstract:
Basswood was transformed by high-temperature pyrolysis into carbon performs (charcoal) and subsequently converted into cellular SiC-ceramics possessing pseudomorphous microstructure by the reactive-infiltration of Si into CB-template in Ar atmos- phere.Thermogravimetric analysis (TGA) was applied to reveal the pyrolysis behavior of basswood powder.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize and analyze the microstructures and phase identification of CB-template and final SiC ceramics.The infiltration mechanism of liquid Si into charcoal and the basic properties of cellular SiC were also given.The results showed that CB-template was amorphous carbon materials.Final cellular SiC was composed of the major phase ?-SiC and a little unreacted carbon.Compared to charcoal,cellular SiC possessed higher mechanical properties.The improvement of the mechanical properties of materials was mainly caused by the following factors:one was the conversion of carbon fibres into SiC fibres,and the another was the volume expansion during CB-template-to-cellular SiC conversion,which inhibited the initiation and propagation of cracks and made cracks deflect.
Basswood was transformed by high-temperature pyrolysis into carbon performs (charcoal) and subsequently converted into cellular SiC-ceramics possessing pseudomorphous microstructure by the reactive-infiltration of Si into CB-template in Ar atmos- phere.Thermogravimetric analysis (TGA) was applied to reveal the pyrolysis behavior of basswood powder.Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were employed to characterize and analyze the microstructures and phase identification of CB-template and final SiC ceramics.The infiltration mechanism of liquid Si into charcoal and the basic properties of cellular SiC were also given.The results showed that CB-template was amorphous carbon materials.Final cellular SiC was composed of the major phase ?-SiC and a little unreacted carbon.Compared to charcoal,cellular SiC possessed higher mechanical properties.The improvement of the mechanical properties of materials was mainly caused by the following factors:one was the conversion of carbon fibres into SiC fibres,and the another was the volume expansion during CB-template-to-cellular SiC conversion,which inhibited the initiation and propagation of cracks and made cracks deflect.
2004, 33(10):1069-1071.
Abstract:
Microhardness testing was conducted on a series of TiCN-based cermets with different contents of metallic binders (5 binders, Mo?Ni=2?1) in the applied load range from 0.49 N to 9.8 N. Significant indentation size effect in the measured microhardness was observed for each test sample. Based on the energy-balance consideration, a new theoretical explanation is presented for the indentation size effect of microhardness of test sample. It is shown that only part of the work done by applied load has been transformed into the energy to cause the irreversible volume deformation of material during indentation. The extra dissipation of the work done by applied load is the main cause for decreasing tendency of microhardness with increased indentation size. The load-independent hardness was found to decrease with the increasing metallic binder content. This can be attributed to the fact that the hardnesses of metallic binders are lower than that of the TiCN matrix.
Microhardness testing was conducted on a series of TiCN-based cermets with different contents of metallic binders (5 binders, Mo?Ni=2?1) in the applied load range from 0.49 N to 9.8 N. Significant indentation size effect in the measured microhardness was observed for each test sample. Based on the energy-balance consideration, a new theoretical explanation is presented for the indentation size effect of microhardness of test sample. It is shown that only part of the work done by applied load has been transformed into the energy to cause the irreversible volume deformation of material during indentation. The extra dissipation of the work done by applied load is the main cause for decreasing tendency of microhardness with increased indentation size. The load-independent hardness was found to decrease with the increasing metallic binder content. This can be attributed to the fact that the hardnesses of metallic binders are lower than that of the TiCN matrix.
2004, 33(10):1072-1075.
Abstract:
TiB2-Cu-Ni five-layer metal-ceramic functionally graded material (FGM) was produced by self-propagating high- temperature synthesis (SHS) under the conditions of pseudo hot isostatic pressing (PHIP). The microstructure and composition of the FGM before and after test were examined by SEM and EPMA etc. The FGM was heated for 20 seconds by plasma torch arc heater to investigate thermal shock resistance and ablation behaviour. The results show that the stacked interface between layer and layer of FGM is obscure, which shows that the bonding between layer and layer is good. The FGM did not burst apart when the surface temperatures of FGM increased and went down drastically in a very short moment. Moreover, no apparent cracks were found on the ablation surface of FGM. These results show that the thermal shock resistance of FGM is excellent. The mass loss of FGM after ablation test is only 0.5 g, which shows that the resistance to ablation and erosion of FGM is good. The ablation mechanisms of the material are volatilization of metal binder, hot chemical ablation and mechanical erosion. This FGM can be used widely as nozzle and throat in the solid rocket motor.
TiB2-Cu-Ni five-layer metal-ceramic functionally graded material (FGM) was produced by self-propagating high- temperature synthesis (SHS) under the conditions of pseudo hot isostatic pressing (PHIP). The microstructure and composition of the FGM before and after test were examined by SEM and EPMA etc. The FGM was heated for 20 seconds by plasma torch arc heater to investigate thermal shock resistance and ablation behaviour. The results show that the stacked interface between layer and layer of FGM is obscure, which shows that the bonding between layer and layer is good. The FGM did not burst apart when the surface temperatures of FGM increased and went down drastically in a very short moment. Moreover, no apparent cracks were found on the ablation surface of FGM. These results show that the thermal shock resistance of FGM is excellent. The mass loss of FGM after ablation test is only 0.5 g, which shows that the resistance to ablation and erosion of FGM is good. The ablation mechanisms of the material are volatilization of metal binder, hot chemical ablation and mechanical erosion. This FGM can be used widely as nozzle and throat in the solid rocket motor.
2004, 33(10):1076-1079.
Abstract:
Photo-catalytic nano titanium dioxide film has been prepared by electrochemical oxidation process. The microstructure and grain morphology in the film are characterized by TEM and XRD. The photo absorption character of the film is measured using spectrometer. It shows that porous amorphous titanium dioxide films are formed by the electrochemical oxidation process in the dielectric solution at an applied voltage and temperature. The amorphous film transforms into nano crystallized titanium dioxide film with anatase structure by means of heat treatment. The oxidation current density decrease with time increase at the voltage of 0~80 V in logarithm law. The grain size in the film is about 20 nm~40 nm. The film has high photo catalytic activity as demonstrated by the degradation test of acid red B in dye solution.
Photo-catalytic nano titanium dioxide film has been prepared by electrochemical oxidation process. The microstructure and grain morphology in the film are characterized by TEM and XRD. The photo absorption character of the film is measured using spectrometer. It shows that porous amorphous titanium dioxide films are formed by the electrochemical oxidation process in the dielectric solution at an applied voltage and temperature. The amorphous film transforms into nano crystallized titanium dioxide film with anatase structure by means of heat treatment. The oxidation current density decrease with time increase at the voltage of 0~80 V in logarithm law. The grain size in the film is about 20 nm~40 nm. The film has high photo catalytic activity as demonstrated by the degradation test of acid red B in dye solution.
2004, 33(10):1080-1083.
Abstract:
用锆盐的前驱物(ZrO(OH)2)胶体与氯铂酸铵均匀混合．经过高温烧结．得到纳米ZrO2均匀分布于铂的坯料，再通过压力加工方法制成纳米氧化锫/铂复合材料(纳米ZrO2／Pt)的试样。用金相显微镜，扫描电镜(SEM)观察发现，纳米ZrO2颗粒可明显细化基体铂。纳米ZrO2/Pt复合材料的拉伸断口形貌也与纯铂明显不同。在高分辨透射电子显微镜(HREM)下观察可见，ZrO2颗粒周围铂原子排列发生了扭曲，由此导致铂的力学性能发生很大变化．纳米ZrO2/Pt复合材料的抗拉强度(σb)达470MPa．1400℃下的拉伸强度(σb)达15MPa，断裂伸长率(δ)为20％，硬度(HV)为940MPa．分别是纯铂的3．6倍 10倍，0.5倍和2．3倍。
用锆盐的前驱物(ZrO(OH)2)胶体与氯铂酸铵均匀混合．经过高温烧结．得到纳米ZrO2均匀分布于铂的坯料，再通过压力加工方法制成纳米氧化锫/铂复合材料(纳米ZrO2／Pt)的试样。用金相显微镜，扫描电镜(SEM)观察发现，纳米ZrO2颗粒可明显细化基体铂。纳米ZrO2/Pt复合材料的拉伸断口形貌也与纯铂明显不同。在高分辨透射电子显微镜(HREM)下观察可见，ZrO2颗粒周围铂原子排列发生了扭曲，由此导致铂的力学性能发生很大变化．纳米ZrO2/Pt复合材料的抗拉强度(σb)达470MPa．1400℃下的拉伸强度(σb)达15MPa，断裂伸长率(δ)为20％，硬度(HV)为940MPa．分别是纯铂的3．6倍 10倍，0.5倍和2．3倍。
2004, 33(10):1084-1088.
Abstract:
The properties of PW-EVA-HDPE binder with the addition of MW were studied. It shows that the addition of MW from 1% to 30% (mass fraction) causes an increase in the tensile strength and a decrease in shrinkage of the binder. After blending PW with MW, the crystallation behavior of wax matrix changes, that is resulting in fine grain for the binder and more isotropic microstructure for the feedstock. The powder loading capacity increases and the feedstock becomes more homogeneous. The reason of the modification is also discussed.
The properties of PW-EVA-HDPE binder with the addition of MW were studied. It shows that the addition of MW from 1% to 30% (mass fraction) causes an increase in the tensile strength and a decrease in shrinkage of the binder. After blending PW with MW, the crystallation behavior of wax matrix changes, that is resulting in fine grain for the binder and more isotropic microstructure for the feedstock. The powder loading capacity increases and the feedstock becomes more homogeneous. The reason of the modification is also discussed.
2004, 33(10):1089-1092.
Abstract:
针对钛齿表面的氧化渗透问题，配制新型涂料，用熔模铸造法原位制取钛片试样模拟钛齿生产过程。利用能谱(EDX)和X射线衍射(XRD)分析钛片的化学组成和物相，普通金相显微镜观察显微组织。结果表明，配制的新型涂料能将钛片表面氧化渗透层的厚度降至50μm左右，钛片的渗入元素为钨和钇。显微硬度分析表明，钨的渗入恶化了钛片的机械性能和使用性能，在蜡模表面均匀涂敷涂料可消除钇的渗入。钛片表面的氧化渗透是由铸造过程中熔钛与涂料在界面处发生冶金反应的结果。
针对钛齿表面的氧化渗透问题，配制新型涂料，用熔模铸造法原位制取钛片试样模拟钛齿生产过程。利用能谱(EDX)和X射线衍射(XRD)分析钛片的化学组成和物相，普通金相显微镜观察显微组织。结果表明，配制的新型涂料能将钛片表面氧化渗透层的厚度降至50μm左右，钛片的渗入元素为钨和钇。显微硬度分析表明，钨的渗入恶化了钛片的机械性能和使用性能，在蜡模表面均匀涂敷涂料可消除钇的渗入。钛片表面的氧化渗透是由铸造过程中熔钛与涂料在界面处发生冶金反应的结果。
2004, 33(10):1093-1095.
Abstract:
Pure Indium oxide powder was synthesized by chemical precipitation. In2O3 based gas sensing materials doped with noble metal catalyst were made by impregnation. The phase composition of powders was determined with XRD. The gas sensitivity of these side-heated gas sensors were tested in static state by using RQ-2 gas sensitive behaviour analyzer and ploted the curves of gas sensltivity against temperature for several kinds of gas. The results showed that In2O3 based gas sensors can be used to detect gas selectively or generally because of its high gas sensitivity, proper resistance and quick response and recovery.
Pure Indium oxide powder was synthesized by chemical precipitation. In2O3 based gas sensing materials doped with noble metal catalyst were made by impregnation. The phase composition of powders was determined with XRD. The gas sensitivity of these side-heated gas sensors were tested in static state by using RQ-2 gas sensitive behaviour analyzer and ploted the curves of gas sensltivity against temperature for several kinds of gas. The results showed that In2O3 based gas sensors can be used to detect gas selectively or generally because of its high gas sensitivity, proper resistance and quick response and recovery.
2004, 33(10):1096-1099.
Abstract:
采用溶胶-浸渍法，成功地在三维编织碳纤维的纤维表面涂覆SiO2，并通过碳热还原反应制得厚度约为0．55gm的SiC涂层。研究了涂层／编织碳纤维(复合纤维)氧化反应的动力学和反应机理。结果表明：涂层能明显提高编织碳纤维的抗氧化性能：复合纤维的氧化反应过程可以分为2个阶段：第1阶段为反应控制；第2阶段为扩散和反应共同控制。
采用溶胶-浸渍法，成功地在三维编织碳纤维的纤维表面涂覆SiO2，并通过碳热还原反应制得厚度约为0．55gm的SiC涂层。研究了涂层／编织碳纤维(复合纤维)氧化反应的动力学和反应机理。结果表明：涂层能明显提高编织碳纤维的抗氧化性能：复合纤维的氧化反应过程可以分为2个阶段：第1阶段为反应控制；第2阶段为扩散和反应共同控制。
2004, 33(10):1100-1103.
Abstract:
通过对某种铸态和预淬火态亚共析U-Nb合金样品的900℃等温淬火实验，利用金相显微镜(OM)，透射电镜(TEM)和X射线衍射(XRD)等方法研究了单靠热处理工艺细化该种铸态合金晶粒的可行性。实验结果表明，由a y1-2两相组成的铸态样品在a y1-2→y1等温转变过程中没有明显的重结晶行为，y1新相的晶粒特征表现为原y1晶界的平直化迁移，因此淬火后晶粒不能细化；由单一a″相组成的预淬火态样品在a″→y1等温转变过程中则发生完全重结晶，等温0．25h能使晶粒尺寸减小1倍。分析认为，该种铸态合金通过预淬火处理使晶格缺陷增多，以及所生成的单一a″相中存在大量的孪晶结构降低了等温转变时y1新相的形核能导致了a″→y1等温转变发生重结晶。结论认为，采取两次淬火的热处理方法可以细化该种铸态亚共析U-Nb合金晶粒。
通过对某种铸态和预淬火态亚共析U-Nb合金样品的900℃等温淬火实验，利用金相显微镜(OM)，透射电镜(TEM)和X射线衍射(XRD)等方法研究了单靠热处理工艺细化该种铸态合金晶粒的可行性。实验结果表明，由a y1-2两相组成的铸态样品在a y1-2→y1等温转变过程中没有明显的重结晶行为，y1新相的晶粒特征表现为原y1晶界的平直化迁移，因此淬火后晶粒不能细化；由单一a″相组成的预淬火态样品在a″→y1等温转变过程中则发生完全重结晶，等温0．25h能使晶粒尺寸减小1倍。分析认为，该种铸态合金通过预淬火处理使晶格缺陷增多，以及所生成的单一a″相中存在大量的孪晶结构降低了等温转变时y1新相的形核能导致了a″→y1等温转变发生重结晶。结论认为，采取两次淬火的热处理方法可以细化该种铸态亚共析U-Nb合金晶粒。
2004, 33(10):1108-1111.
Abstract:
The phases formed by erbium in alloys with 5.6%Zn, 1.9% Mg, 1.6% Cu,1.0% Li,0.3% Er(wt%) is investigated by TEM. Most of erbium is formed with aluminum to Al3Er phases which look like block, dot, lath or worm. Some of Al3Er phases are coherent with alloys matrix, and fine Al3Er phases can be sites for ? (MgZn2) heterogeneous precipitation. Saturated erbium is segregated to grain boundary seriously and there is small Al3Er phase in grain boundary, where precipitates are not continuous.
The phases formed by erbium in alloys with 5.6%Zn, 1.9% Mg, 1.6% Cu,1.0% Li,0.3% Er(wt%) is investigated by TEM. Most of erbium is formed with aluminum to Al3Er phases which look like block, dot, lath or worm. Some of Al3Er phases are coherent with alloys matrix, and fine Al3Er phases can be sites for ? (MgZn2) heterogeneous precipitation. Saturated erbium is segregated to grain boundary seriously and there is small Al3Er phase in grain boundary, where precipitates are not continuous.
2004, 33(10):1112-1115.
Abstract:
测量和比较Zr-4合金样品分别在400℃，10.3MPa过热水蒸汽，0．01mol／L和0．04mol／L的LiOH水溶液中腐蚀后氧化膜／金属界面处氧化膜内的压应力，发现在0．04mol／L LiOH水溶液中腐蚀样品的压应力始终低于在0．01mol／L LiOH水溶液中腐蚀的样品，也始终低于在400℃水蒸汽中腐蚀的样品；0．01mol／L LiOH水溶液中腐蚀的样品，其界面处的压应力在氧化膜达到一定厚度后也低于在400℃水蒸汽中腐蚀的样品。这表明一定浓度的LiOH水溶液在氧化膜生成过程中会降低氧化膜中的压应力，LiOH水溶液浓度越高，这种作用越明显。
测量和比较Zr-4合金样品分别在400℃，10.3MPa过热水蒸汽，0．01mol／L和0．04mol／L的LiOH水溶液中腐蚀后氧化膜／金属界面处氧化膜内的压应力，发现在0．04mol／L LiOH水溶液中腐蚀样品的压应力始终低于在0．01mol／L LiOH水溶液中腐蚀的样品，也始终低于在400℃水蒸汽中腐蚀的样品；0．01mol／L LiOH水溶液中腐蚀的样品，其界面处的压应力在氧化膜达到一定厚度后也低于在400℃水蒸汽中腐蚀的样品。这表明一定浓度的LiOH水溶液在氧化膜生成过程中会降低氧化膜中的压应力，LiOH水溶液浓度越高，这种作用越明显。
2004, 33(10):1116-1119.
Abstract:
Ce0.67Tb0.33MgAl11O19: Gd3+ has been synthesized by processing of sol-gel, the influence of Gd doping on fluorescence of Ce0.67Tb0.33MgAl11O19 was investigated by changing the concentration and the substituted object of Gd3+ ion. The effects of substituting a part of Ce and a part of Tb with Ga on fluorescence of Ce0.67Tb0.33MgAl11O19 was studied respectively. Gd3+ transfers the energy absorbed by Ce3+ to Tb3+ efficiently, so the fluorescence intensity of Ce0.67Tb0.33MgAl11O19 changed less when Gd3+ is doped into Ce0.67Tb0.33MgAl11O19, even enhanced to some extent, And the emission color of Ce0.67Tb0.33MgAl11O19 will change a little.
Ce0.67Tb0.33MgAl11O19: Gd3+ has been synthesized by processing of sol-gel, the influence of Gd doping on fluorescence of Ce0.67Tb0.33MgAl11O19 was investigated by changing the concentration and the substituted object of Gd3+ ion. The effects of substituting a part of Ce and a part of Tb with Ga on fluorescence of Ce0.67Tb0.33MgAl11O19 was studied respectively. Gd3+ transfers the energy absorbed by Ce3+ to Tb3+ efficiently, so the fluorescence intensity of Ce0.67Tb0.33MgAl11O19 changed less when Gd3+ is doped into Ce0.67Tb0.33MgAl11O19, even enhanced to some extent, And the emission color of Ce0.67Tb0.33MgAl11O19 will change a little.
