Volume 33,Issue 4,2004 Table of Contents
2004, 33(4):337-342.
Abstract:
Research and development of 2:17 type SmCo permanent magnets are reviewed. Considered are four magnets types : high temperature magnets, super-low temperature coefficient magnets, the radially oriented and multi-polar rings, high electricity insulation magnets. Manufacturing techniques described include: powder metallurgy (sintering), reverting-diffuse and quenching-bonding. The cellular microstructure was characterized, and the effects of components on microstructure were discussed. The coercivity mechanism over a wide temperature range was considered and directions for future research discussed.
Research and development of 2:17 type SmCo permanent magnets are reviewed. Considered are four magnets types : high temperature magnets, super-low temperature coefficient magnets, the radially oriented and multi-polar rings, high electricity insulation magnets. Manufacturing techniques described include: powder metallurgy (sintering), reverting-diffuse and quenching-bonding. The cellular microstructure was characterized, and the effects of components on microstructure were discussed. The coercivity mechanism over a wide temperature range was considered and directions for future research discussed.
2004, 33(4):343-348.
Abstract:
The preparation of nanostructured materials is discussed in the light of previous techniques used for the preparation of nano-scale TiO2. Almost all methods for successfully preparing nano-structured materials can be divided into two categories depending on the sizes of the interacting particles; such processes are designated coacervation and dispersion. These two processes not only provide the new way to design the new type materials but also boost materials processing science to a new level.
The preparation of nanostructured materials is discussed in the light of previous techniques used for the preparation of nano-scale TiO2. Almost all methods for successfully preparing nano-structured materials can be divided into two categories depending on the sizes of the interacting particles; such processes are designated coacervation and dispersion. These two processes not only provide the new way to design the new type materials but also boost materials processing science to a new level.
2004, 33(4):349-353.
Abstract:
Much research worldwide is concentrated on nano-cemented carbide due to its excellent properties and promising market prospect. This paper reviewes some developments in nano-cemented carbide. New fast sintering techniques should be employed because the key to obtaining nano-cemented carbide is to control the WC grain growth during sintering.
Much research worldwide is concentrated on nano-cemented carbide due to its excellent properties and promising market prospect. This paper reviewes some developments in nano-cemented carbide. New fast sintering techniques should be employed because the key to obtaining nano-cemented carbide is to control the WC grain growth during sintering.
2004, 33(4):354-358.
Abstract:
This paper describes the basic concepts, characteristics and material composition of photonic crystals. Self-assembly techniques of preparing three-dimensional semiconductor photonic crystals are introduced in detail. In order to increase the refractive index contrast of the electrolyte, inverted opal is prepared by utilizing a synthetic opal as a template. Finally, we discuss applications of photonic crystals.
This paper describes the basic concepts, characteristics and material composition of photonic crystals. Self-assembly techniques of preparing three-dimensional semiconductor photonic crystals are introduced in detail. In order to increase the refractive index contrast of the electrolyte, inverted opal is prepared by utilizing a synthetic opal as a template. Finally, we discuss applications of photonic crystals.
2004, 33(4):359-362.
Abstract:
研究了SiC/TC4和SiC／Ti40复合材料在不同热处理态下的界面行为。结果袭明，SiC／Ti40复合材料相邻两纤维间存在TiC析出物，在1000℃处理后，TiC析出物消失；2种复合材料界面反应厚度随处理温度升高和时间延长而增大：SCS-6SiC／TC4和SiC／Ti40复合材料界面产物均为Ti5Si3。
研究了SiC/TC4和SiC／Ti40复合材料在不同热处理态下的界面行为。结果袭明，SiC／Ti40复合材料相邻两纤维间存在TiC析出物，在1000℃处理后，TiC析出物消失；2种复合材料界面反应厚度随处理温度升高和时间延长而增大：SCS-6SiC／TC4和SiC／Ti40复合材料界面产物均为Ti5Si3。
2004, 33(4):363-367.
Abstract:
Four kinds of microstructural instability of a TiAl-based alloy during rapid heating cyclic heat treatment were observed: (i) the formation of secondary lamellae, (ii) the spheroidization of primary lamellae, (iii) a discontinuous coarsening at grain boundaries and (iv) nucleation at phase interfaces. By comparing the starting line of continuous heating transformation with that of TTT diagram, the similarity and difference of the microstructure instability during continuous heating and isothermal heating conditions were studied. Ways of avoiding unfavorable microstructural instability were proposed such as: (i) insuring homogeneity of the composition so as to guarantee the identity of transformation temperature in the alloy; (ii) holding at the highest temperature for as short a time as possible.
Four kinds of microstructural instability of a TiAl-based alloy during rapid heating cyclic heat treatment were observed: (i) the formation of secondary lamellae, (ii) the spheroidization of primary lamellae, (iii) a discontinuous coarsening at grain boundaries and (iv) nucleation at phase interfaces. By comparing the starting line of continuous heating transformation with that of TTT diagram, the similarity and difference of the microstructure instability during continuous heating and isothermal heating conditions were studied. Ways of avoiding unfavorable microstructural instability were proposed such as: (i) insuring homogeneity of the composition so as to guarantee the identity of transformation temperature in the alloy; (ii) holding at the highest temperature for as short a time as possible.
2004, 33(4):368-371.
Abstract:
利用X射线衍射技术测试了TiC颗粒增强钛基复合材料Ti-6Al-4V 7％TiC(质量分数，下同)(T64)，Ti-3Al-2．5V 7％TiC(T32)和Ti-6Al-2．5Sn-4Zr-0．5Mo-1Nb-0．45Si 3％TiC(T650)的内应力。发现该复合材料在800℃左右存在一个应力性质转变点，即在800℃以上处理，钛基体感生残余拉应力，增强TiC颗粒感生残余压应力；在800℃以下处理，应力性质相反。并且内应力随处理温度升高而增加，由Eshelby模型得出，该转变点和钛合金基体的相变点有关。
利用X射线衍射技术测试了TiC颗粒增强钛基复合材料Ti-6Al-4V 7％TiC(质量分数，下同)(T64)，Ti-3Al-2．5V 7％TiC(T32)和Ti-6Al-2．5Sn-4Zr-0．5Mo-1Nb-0．45Si 3％TiC(T650)的内应力。发现该复合材料在800℃左右存在一个应力性质转变点，即在800℃以上处理，钛基体感生残余拉应力，增强TiC颗粒感生残余压应力；在800℃以下处理，应力性质相反。并且内应力随处理温度升高而增加，由Eshelby模型得出，该转变点和钛合金基体的相变点有关。
2004, 33(4):372-374.
Abstract:
压缩天然气(CNG)汽车因其良好的排放特性，正被越来越多的大型城市公交系统使用，但是汽油车辆用尾气净化催化荒对天然气汽车的主要烃类排放物甲烷转化效率低。针对天然气车辆排放物特点，设计了天然气汽车尾气净化催化剂，其成分包括稀土金属和过渡金属化合物、少量贵金属氧化物、结构稳定剂等。试验结果表明，在700℃以上，CO和CH4转化率达到98％以上，催化剂耐高温性能好，在1000℃，1．5h试验时间内HC和CO转化率达到99％，此外该催化剂具有一定的抗硫化物中毒能力。
压缩天然气(CNG)汽车因其良好的排放特性，正被越来越多的大型城市公交系统使用，但是汽油车辆用尾气净化催化荒对天然气汽车的主要烃类排放物甲烷转化效率低。针对天然气车辆排放物特点，设计了天然气汽车尾气净化催化剂，其成分包括稀土金属和过渡金属化合物、少量贵金属氧化物、结构稳定剂等。试验结果表明，在700℃以上，CO和CH4转化率达到98％以上，催化剂耐高温性能好，在1000℃，1．5h试验时间内HC和CO转化率达到99％，此外该催化剂具有一定的抗硫化物中毒能力。
2004, 33(4):380-384.
Abstract:
The P (MMA-co-St) copolymer containing dysprosium was prepared by the in-situ polymerization of a gel, which was obtained by doping directly dysprosium tri-isopropoxide in the monomer mixtures of methyl methacrylate and styrene (monomer mole ratio was 1:1). The effect of dysprosium tri-isopropoxide on the properties of P (MMA-co-St) copolymer was also studied. It was shown that the linear structure of P (MMA-co-St) containing dysprosium changed into a crosslinked network with increasing dysprosium content, resulting in improvement of properties, such as resistance to heat and solvent, storage modulus and fluorescence strength. Moreover the copolymer is a material with high uniformly distributed rare earth content and improved transparency.
The P (MMA-co-St) copolymer containing dysprosium was prepared by the in-situ polymerization of a gel, which was obtained by doping directly dysprosium tri-isopropoxide in the monomer mixtures of methyl methacrylate and styrene (monomer mole ratio was 1:1). The effect of dysprosium tri-isopropoxide on the properties of P (MMA-co-St) copolymer was also studied. It was shown that the linear structure of P (MMA-co-St) containing dysprosium changed into a crosslinked network with increasing dysprosium content, resulting in improvement of properties, such as resistance to heat and solvent, storage modulus and fluorescence strength. Moreover the copolymer is a material with high uniformly distributed rare earth content and improved transparency.
2004, 33(4):385-388.
Abstract:
The deformation behavior of the alloy Ti14 in the semi-solid state has been studied. The results show that the liquid phase enhances the diffusivity of the constituents. The semi-solid deformation energy is more than that of solid deformation. When the Ti14 alloy is semi-solid deformed, the liquid Ti2Cu phase within grains and grain boundaries grows, thereby forming broadened grain boundaries and network structures.
The deformation behavior of the alloy Ti14 in the semi-solid state has been studied. The results show that the liquid phase enhances the diffusivity of the constituents. The semi-solid deformation energy is more than that of solid deformation. When the Ti14 alloy is semi-solid deformed, the liquid Ti2Cu phase within grains and grain boundaries grows, thereby forming broadened grain boundaries and network structures.
2004, 33(4):389-392.
Abstract:
A newly designed Bi2223 tape incorporating an Ag alloy wire in superconducting core is described. It is shown that the new structure considerably improves the superconducting properties of monofilament tapes. The maximum Ic is as high as 75 A, and Jc= 1.6104A/cm2 , increases of 30% over those of conventional superconductor tape. At the same time the mechanical properties of the new Bi2223 tape show considerable improvement.
A newly designed Bi2223 tape incorporating an Ag alloy wire in superconducting core is described. It is shown that the new structure considerably improves the superconducting properties of monofilament tapes. The maximum Ic is as high as 75 A, and Jc= 1.6104A/cm2 , increases of 30% over those of conventional superconductor tape. At the same time the mechanical properties of the new Bi2223 tape show considerable improvement.
2004, 33(4):393-396.
Abstract:
The fractal characteristics of reduced cobalt powders for Powder Injection Molding (PIM), such as powder shape, projection border, and powder surface, are studied. A simple and suitable method which can be used to measure the dimensions of the fractal structure of particle profiles is introduced. An accurate quantitative method for characterizing powders for PIM using fractal geometric nomenclature is given. From the scanning electron micrograph, the fractal dimensions of the projected profile of reduced cobalt powders are calculated using the In Swing Structured Walk technique. Fractal dimensions obtained were in the range of 1.116 to 1.122.
The fractal characteristics of reduced cobalt powders for Powder Injection Molding (PIM), such as powder shape, projection border, and powder surface, are studied. A simple and suitable method which can be used to measure the dimensions of the fractal structure of particle profiles is introduced. An accurate quantitative method for characterizing powders for PIM using fractal geometric nomenclature is given. From the scanning electron micrograph, the fractal dimensions of the projected profile of reduced cobalt powders are calculated using the In Swing Structured Walk technique. Fractal dimensions obtained were in the range of 1.116 to 1.122.
2004, 33(4):397-399.
Abstract:
A hydroxylapatite (HA) coating was produced by means of bionic mineralizing in a fast calcific solution(FCS)at room temperature. The pH changes of FCS during the deposition process were measured. The supersaturations of various calcium phosphates formed during FCS were compared, during which that of HA was found to be the greatest. Optimnal thermodynamic conditions were important for the formation of HA coatings in the bionic mineralizing process.
A hydroxylapatite (HA) coating was produced by means of bionic mineralizing in a fast calcific solution(FCS)at room temperature. The pH changes of FCS during the deposition process were measured. The supersaturations of various calcium phosphates formed during FCS were compared, during which that of HA was found to be the greatest. Optimnal thermodynamic conditions were important for the formation of HA coatings in the bionic mineralizing process.
2004, 33(4):400-403.
Abstract:
在IN738镍基高温合金上，采用低压固体粉末包埋渗铝方法制备钯改性铝化物涂层。利用TGA、XRD、SEM以及金相等方法，研究了Pd-Ni-Al涂层在1050℃的高温氧化行为。结果表明：与NiAl涂层相比，Pd-Ni-Al涂层表面氧化膜粘附性优良，改性涂层的退化相γ'远少于普通NiAl涂层，显示出优良的高温稳定性。添加改性元素Pd，提高了铝化物涂层的抗循环氧化性能。
在IN738镍基高温合金上，采用低压固体粉末包埋渗铝方法制备钯改性铝化物涂层。利用TGA、XRD、SEM以及金相等方法，研究了Pd-Ni-Al涂层在1050℃的高温氧化行为。结果表明：与NiAl涂层相比，Pd-Ni-Al涂层表面氧化膜粘附性优良，改性涂层的退化相γ'远少于普通NiAl涂层，显示出优良的高温稳定性。添加改性元素Pd，提高了铝化物涂层的抗循环氧化性能。
2004, 33(4):404-407.
Abstract:
The microstructure and mechanical properties of AlCuMgAg doped with Ce and Ti were investigated by tensile testing and microstructure analysis. It is shown that Ce and Ti doping increases the hardness and improves the tensile strength. Moreover, the Ce doping can improve the heat resistance of the alloy. By microstructure analysis, it is shown that the kinds of the precipitation- strengthening phases are not changed, although they decrease in size and increase in density. When both Ce and Ti were doped into the AlCuMgAg alloy, a new AlTiCeCu compound that is harder and brittle is formed, the precipitated phases were inhibited, and the tensile strength of the alloy decreased.
The microstructure and mechanical properties of AlCuMgAg doped with Ce and Ti were investigated by tensile testing and microstructure analysis. It is shown that Ce and Ti doping increases the hardness and improves the tensile strength. Moreover, the Ce doping can improve the heat resistance of the alloy. By microstructure analysis, it is shown that the kinds of the precipitation- strengthening phases are not changed, although they decrease in size and increase in density. When both Ce and Ti were doped into the AlCuMgAg alloy, a new AlTiCeCu compound that is harder and brittle is formed, the precipitated phases were inhibited, and the tensile strength of the alloy decreased.
2004, 33(4):408-411.
Abstract:
对集束拉拔法制备的不锈钢纤维进行150℃~800℃退火热处理,用VSM测试热处理后的纤维磁性,用X射线衍射仪、扫描电子显微镜进行相分析。结果表明:热处理对304不锈钢纤维磁性影响较大,2 m的304不锈钢纤维在180℃附近退火,有回火马氏体生成,纤维的饱和磁化强度(Ms)增加,此后该温度范围内退火纤维的Ms降低;400℃热处理使得纤维矫顽力Hc增加较大,同时磁能积(Mr×Hc)配合较好,退火后可用作磁性纤维。热处理对316 L不锈钢纤维的力学性能影响明显。
对集束拉拔法制备的不锈钢纤维进行150℃~800℃退火热处理,用VSM测试热处理后的纤维磁性,用X射线衍射仪、扫描电子显微镜进行相分析。结果表明:热处理对304不锈钢纤维磁性影响较大,2 m的304不锈钢纤维在180℃附近退火,有回火马氏体生成,纤维的饱和磁化强度(Ms)增加,此后该温度范围内退火纤维的Ms降低;400℃热处理使得纤维矫顽力Hc增加较大,同时磁能积(Mr×Hc)配合较好,退火后可用作磁性纤维。热处理对316 L不锈钢纤维的力学性能影响明显。
2004, 33(4):412-416.
Abstract:
采用SHS反应火焰喷涂工艺在钢基表面制备了以Al2O3-Al2Cu3相为主的复相涂层。测定了涂层的物相组成与组织结构，分析了在热喷涂工艺条件下涂层的形成过程，实验了物料预热、基材预热以及喷涂距离对涂层组织结构和机械物理性能的影响规律。提出：在SHS反应喷涂中与物理过程同时进行的化学燃烧与结构转变过程经历预热、SHS燃烧反应和结构形成与凝固3个阶段，所得涂层中部分Al2O3以较大尺寸片状分布于不同Al-Cu区域边界，部分以100nm到几微米的颗粒状和球状弥散分布于Al2Cu3基体的内部，形成内晶型结构；物料预热温度、基材预热及喷涂距离等参数通过影响反应转化程度和反应能量而对涂层组织结构和机械物理性能有较大影响，实验表明涂层组织与性能在基材预热、物料预热温度为250℃以上、喷涂距离在200mm左右时较为理想。
采用SHS反应火焰喷涂工艺在钢基表面制备了以Al2O3-Al2Cu3相为主的复相涂层。测定了涂层的物相组成与组织结构，分析了在热喷涂工艺条件下涂层的形成过程，实验了物料预热、基材预热以及喷涂距离对涂层组织结构和机械物理性能的影响规律。提出：在SHS反应喷涂中与物理过程同时进行的化学燃烧与结构转变过程经历预热、SHS燃烧反应和结构形成与凝固3个阶段，所得涂层中部分Al2O3以较大尺寸片状分布于不同Al-Cu区域边界，部分以100nm到几微米的颗粒状和球状弥散分布于Al2Cu3基体的内部，形成内晶型结构；物料预热温度、基材预热及喷涂距离等参数通过影响反应转化程度和反应能量而对涂层组织结构和机械物理性能有较大影响，实验表明涂层组织与性能在基材预热、物料预热温度为250℃以上、喷涂距离在200mm左右时较为理想。
2004, 33(4):417-420.
Abstract:
研究了600℃时Fe-15Ce合金在H2-CO2、H2-H2S及H2-H2S-CO2 3种气氛中的腐蚀行为，Fe-15Ce合金腐蚀后发生了Ce的内氧化或形成了复杂的腐蚀产物膜，而未出现Ce的选择性氧化或硫化，这主要是合金中存在着两相及Ce在Fe中极低的溶解度的结果。Fe-15Ce合金在本实验条件下的氧化-硫化腐蚀速度低于相同温度、压力下的纯硫化。
研究了600℃时Fe-15Ce合金在H2-CO2、H2-H2S及H2-H2S-CO2 3种气氛中的腐蚀行为，Fe-15Ce合金腐蚀后发生了Ce的内氧化或形成了复杂的腐蚀产物膜，而未出现Ce的选择性氧化或硫化，这主要是合金中存在着两相及Ce在Fe中极低的溶解度的结果。Fe-15Ce合金在本实验条件下的氧化-硫化腐蚀速度低于相同温度、压力下的纯硫化。
19 Preparation of La0.9Sr0.1Ga0.8Mg0.2O2.85 Ultrafine Powder by Low Temperature Combustion Synthesis
2004, 33(4):421-424.
Abstract:
Low temperature combustion synthesis (LTCS) combines the advantage of solution-based processing with that of high temperature self-propagation. The process can be ignited at low temperature and is sustained by a strong exothermic reaction. As presently described the LTCS process was applied to directly synthesize La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM1020) ultra-fine powder in nitrate-citric acid solution. The LSGM1020 powder prepared by this method has specific surface area as high as 120 m2/g. The effect of solution initial concentration and pH value on the properties of the final powder was investigated.
Low temperature combustion synthesis (LTCS) combines the advantage of solution-based processing with that of high temperature self-propagation. The process can be ignited at low temperature and is sustained by a strong exothermic reaction. As presently described the LTCS process was applied to directly synthesize La0.9Sr0.1Ga0.8Mg0.2O2.85 (LSGM1020) ultra-fine powder in nitrate-citric acid solution. The LSGM1020 powder prepared by this method has specific surface area as high as 120 m2/g. The effect of solution initial concentration and pH value on the properties of the final powder was investigated.
2004, 33(4):425-428.
Abstract:
By mixing NiCl2 and NH4HCO3 solutions at room temperature, NiO nano-particles were synthesized by hydrothermal modification and sintering. The agglomerated amorphous precipitates formed at room temperature were mainly composed of NiCO3. Ni(OH)2 and Ni(OH)2 crystallites and were converted to deposits with higher crystallinity and less content of Ni (OH)2 and H2O after hydrothermal treatment. NiO nano-particles prepared from the hydrothermal deposits were of higher dispersion than those from the amorphous precipitates. The primary thermodynamic calculation in Ni2+-NH3-CO32--H2O system indicated that the rise of temperature is favorable for the release of Ni2+ from the Ni2+-NH3 complex ions, accelerating the formation of NiCO3 and Ni (OH)2. The thermodynamic possibility for the formation of NiCO3 phase increased with the increase of temperature.
By mixing NiCl2 and NH4HCO3 solutions at room temperature, NiO nano-particles were synthesized by hydrothermal modification and sintering. The agglomerated amorphous precipitates formed at room temperature were mainly composed of NiCO3. Ni(OH)2 and Ni(OH)2 crystallites and were converted to deposits with higher crystallinity and less content of Ni (OH)2 and H2O after hydrothermal treatment. NiO nano-particles prepared from the hydrothermal deposits were of higher dispersion than those from the amorphous precipitates. The primary thermodynamic calculation in Ni2+-NH3-CO32--H2O system indicated that the rise of temperature is favorable for the release of Ni2+ from the Ni2+-NH3 complex ions, accelerating the formation of NiCO3 and Ni (OH)2. The thermodynamic possibility for the formation of NiCO3 phase increased with the increase of temperature.
2004, 33(4):429-431.
Abstract:
According to the characteristics of hollow billets, a hot-top electromagnetic continuous casting process is proposed, based on a combination of the hot-top technique and a cold crucible. Sn-4.5%Pb (wt%) was used as the experimental material to study the effect of hot-top and cold crucible outer mould on the distribution of electromagnetic field. The effect of the electromagnetic field on the quality of hollow billets was analyzed. The results indicated that use of the hot-top with screen and cold crucible outer mould, while imposing an electro- magnetic field of 12 kW with the frequency of 2 500, can improve the distribution of electromagnetic field in the mold. In this ways high quality hollow billets can be obtained, whose solidification macrostructure consists of equiaxed grains of high ratio and a smoother surface.
According to the characteristics of hollow billets, a hot-top electromagnetic continuous casting process is proposed, based on a combination of the hot-top technique and a cold crucible. Sn-4.5%Pb (wt%) was used as the experimental material to study the effect of hot-top and cold crucible outer mould on the distribution of electromagnetic field. The effect of the electromagnetic field on the quality of hollow billets was analyzed. The results indicated that use of the hot-top with screen and cold crucible outer mould, while imposing an electro- magnetic field of 12 kW with the frequency of 2 500, can improve the distribution of electromagnetic field in the mold. In this ways high quality hollow billets can be obtained, whose solidification macrostructure consists of equiaxed grains of high ratio and a smoother surface.
2004, 33(4):432-435.
Abstract:
研究了铝板表面前处理以及阳极氧化过程中电解液温度对阳极氧化膜层抗热冲击性能的影响,并分析了影响机理.选择合适的前处理及阳极氧化工艺参数,可以制备具有优良性能的"理想"绝缘金属基板,其阳极氧化绝缘层的电阻率大于1013Ω·cm,击穿电压大于600 V,并且能够抵抗400℃热冲击.采用化学镀铜结合电镀铜工艺对基板进行金属化布线后,"理想"绝缘金属基板被应用于BGA封装中.
研究了铝板表面前处理以及阳极氧化过程中电解液温度对阳极氧化膜层抗热冲击性能的影响,并分析了影响机理.选择合适的前处理及阳极氧化工艺参数,可以制备具有优良性能的"理想"绝缘金属基板,其阳极氧化绝缘层的电阻率大于1013Ω·cm,击穿电压大于600 V,并且能够抵抗400℃热冲击.采用化学镀铜结合电镀铜工艺对基板进行金属化布线后,"理想"绝缘金属基板被应用于BGA封装中.
2004, 33(4):436-438.
Abstract:
By high temperature pack rolling, the first high-Nb TiAl sheet with the thickness of 2.6 mm has been successfully fabricated on a conventional rolling mill. The overall rolling reduction is about 70%, and the surface condition of the sheet is very good. Microstructure observation indicates that during the high temperature rolling, dynamic recrystallization takes place. But the microstructure is not significantly refined by this recrystallization probably on account of the grain growth that occurs during reheating between rolling passes and final furnaccooling.
By high temperature pack rolling, the first high-Nb TiAl sheet with the thickness of 2.6 mm has been successfully fabricated on a conventional rolling mill. The overall rolling reduction is about 70%, and the surface condition of the sheet is very good. Microstructure observation indicates that during the high temperature rolling, dynamic recrystallization takes place. But the microstructure is not significantly refined by this recrystallization probably on account of the grain growth that occurs during reheating between rolling passes and final furnaccooling.
2004, 33(4):439-441.
Abstract:
介绍了1种制备纳米钒催化剂的新方法。用TEM，SEM，XRD，DSC等手段研究了纳米V2O5溶胶．凝胶，以及活性组分V2O5颗粒在钒催化剂中的形貌、大小和分布等。试验结果表明，随着水钒比的降低，纳米V2O5颗粒的形状由针状、椭球状向球状变化：制备纳米V2O5溶胶．凝胶适宜的熔化工艺参数为800℃～860℃，15min～lOmin。采用本工艺方法制备出了含粒径为30nm～60nm的纳米V2O5溶胶-凝胶和纳米钒催化剂。
介绍了1种制备纳米钒催化剂的新方法。用TEM，SEM，XRD，DSC等手段研究了纳米V2O5溶胶．凝胶，以及活性组分V2O5颗粒在钒催化剂中的形貌、大小和分布等。试验结果表明，随着水钒比的降低，纳米V2O5颗粒的形状由针状、椭球状向球状变化：制备纳米V2O5溶胶．凝胶适宜的熔化工艺参数为800℃～860℃，15min～lOmin。采用本工艺方法制备出了含粒径为30nm～60nm的纳米V2O5溶胶-凝胶和纳米钒催化剂。
2004, 33(4):442-444.
Abstract:
A pulp-osseous implant (Ti-6Al-4V) for treating a mobilized periodontal tooth fractured after 15 years of service. The two pieces of implant divided in bone and pulp were extracted and washed by distilled water. The microstructures of the cross sections of both fractured pulp-osseous implant pieces were observed by SEM, and the compositions of the material attached to the implant surfaces were analyzed by EDAX. The fatigue source, slowly and fast developed fatigue stripe is presented were obviously showed on the cross sections of both parts. EDAX showed a higher percentage of Ca, P attached to the bone implant, as compared to that attached to the pulp implant. The fracture of implant in this case was due principally to metal fatigue, and partly caused by a lack of periodontal maintenance.
A pulp-osseous implant (Ti-6Al-4V) for treating a mobilized periodontal tooth fractured after 15 years of service. The two pieces of implant divided in bone and pulp were extracted and washed by distilled water. The microstructures of the cross sections of both fractured pulp-osseous implant pieces were observed by SEM, and the compositions of the material attached to the implant surfaces were analyzed by EDAX. The fatigue source, slowly and fast developed fatigue stripe is presented were obviously showed on the cross sections of both parts. EDAX showed a higher percentage of Ca, P attached to the bone implant, as compared to that attached to the pulp implant. The fracture of implant in this case was due principally to metal fatigue, and partly caused by a lack of periodontal maintenance.
2004, 33(4):445-448.
Abstract:
The X-ray stress constants of five crystalline planes of beryllium were measured by using a cantilever beam loading method on X2001 stress analyzer. The results show that the X-ray stress constant of each plane in beryllium is different, so the X-ray stress constant corresponding to a diffraction plane must be adopted in order to acquire the exact stress value on X-ray stress analysis. Because of the rather large penetrate depth of X-rays into beryllium, that effect on X-ray stress constant measurement must be taken into account.
The X-ray stress constants of five crystalline planes of beryllium were measured by using a cantilever beam loading method on X2001 stress analyzer. The results show that the X-ray stress constant of each plane in beryllium is different, so the X-ray stress constant corresponding to a diffraction plane must be adopted in order to acquire the exact stress value on X-ray stress analysis. Because of the rather large penetrate depth of X-rays into beryllium, that effect on X-ray stress constant measurement must be taken into account.
