MgO—B2O3—SiO2—Al2O3—CaO中含硼组分析晶动力学

根据玻璃形成动力学理论，计算了ＭｇＯ－Ｂ２Ｏ３－ＳｉＯ２－Ａｌ２Ｏ３－ＣａＯ渣系中含硼组分２ＭｇＯ·Ｂ２Ｏ３的成核速度（Ｉ）和晶体长大速度（Ｕ），获得了２ＭｇＯ·Ｂ２Ｏ３晶体形成的最佳温度．采用化学分析、Ｘ射线衍射分析（ＸＲＤ）和差热分析（ＤＴＡ）等方法研究了热处理温度对ＭｇＯ—Ｂ２Ｏ３—ＳｉＯ２—Ａｌ２Ｏ３—ＣａＯ渣系硼提取率的影响．结果表明：硼渣最佳热处理温度与２ＭｇＯ·Ｂ２Ｏ３晶体形成最佳温度一致。     

SiC纤维补强微晶玻璃基复合材料的界面结合

本文通过ＳｉＣ纤维对ＬＣＡＳ（Ｌｉ２Ｏ－ＣａＯ－Ａｌ２Ｏ３－ＳｉＯ２）和ＭＡＳ（ＭｇＯ－Ａｌ２Ｏ３－ＳｉＯ２）微晶玻璃的补强，观察和分析了在不同复合系统中纤维与基体的界面结合。在ＳｉＣ纤维／ＬＣＡＳ微晶玻璃复合系统中，发现纤维与基体之间有一中间界面层，它主要是在复合材料的烧结过程中通过扩散形成，并且于１２００℃时在界面上形成富Ｃ层。ＳｉＣ纤维／ＭＡＳ微晶玻璃基复合材料由于在烧结过程中有化学反应发生     

代稀土无Pb高折射率光学玻璃（TiF700／350）的研究

研究了实用的ＢａＯ－ＴｉＯ２－ＳｉＯ２系代稀土无铅光学玻璃，运用玻璃物理性质的计算方法来拟合玻璃组织，并讨论了可形成稳定玻璃的组成范围，这种玻璃具有高折射率（ｎｄ＝１．７０），低密度（ｐ＝３．０３）与适中的色散系数（Ｖ＝３５），适于实用，Ａｌ２Ｏ３及ＭｇＯ的存在使该系统析晶倾向增大。     

STUDY FOR MECHANICAL ALLOYING OF Fe─M BY MOSSBAUER SPECTROSCOPY

将Ｆｅ－Ｍ（Ｍ＝Ｃ５ＳｉＯ２Ａｌ２Ｏ３）混合物在Ａｒ中高能球磨５６ｇ后测量Ｍｏｓｂａｕｅｒ谱，结果表明，（Ｆｅ）２－（ＳｉＯ２）１仍为Ｆｅ和ＳｉＯ２的机械混合物：（Ｆｅ）６－（Ｃ）３已完全合金化，生成两种Ｆｅ３Ｃ；（Ｆｅ）２－（Ａｌ２Ｏ３）１则成为Ｆｅ（７３％），尖晶石型的ＦｅＡｌ２Ｏ４）２２％），ｑｑｎｔＦｅ的团聚族（５％）和Ａｌ２Ｏ３的混合物。     

表面择优取向析晶β-BaB2O3透明玻璃陶瓷的研究

本文采用传统熔融方法制备了ＢａＯ－Ｂ２Ｏ３系列基础玻璃３（ＢａＯ－Ｂ２Ｏ３、ＢａＯ－Ｂ２Ｏ３－０．１Ａｌ２Ｏ３、ＢａＯ－Ｂ２Ｏ３－０．ＳｉＯ２、ＢａＯ－Ｂ２Ｏ３－０．４ＴｉＯ２）（ｍｏｌ％）通过对基础下班进行表面修饰处理，控制表面析晶条件，获得了含有沿α轴择优到向生长ＢＢＯ微晶的透明ＢａＯ－Ｂ２Ｏ３系列表面析晶玻璃陶瓷。     

CaO—MgO—Fe2O3—Al2O3—SiO2渣系玻璃晶化动力学

根据玻璃形成动力学理论,计算了ＣａＯ－ＭｇＯ－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－ＳｉＯ２渣系中成核速率（Ｉ）和晶体长大速度（Ｕ）,获得晶体形成的最佳温度,研究了热处理温度对ＣａＯ－ＭｇＯ－Ｆｅ２Ｏ３－Ａｌ２Ｏ３－ＳｉＯ２渣系晶体的影响,计算的晶体形成的最佳温度结果表明与该体系的最佳热处理温度一致。     

碳化硅和氧化铝陶瓷的热等静压氮化

通过对无压烧结、热压烧结和热等静压烧结ＳＩＣ陶瓷以及热压烧结的ＳｉＣ粒子补强Ａｌ２Ｏ３基复相陶瓷（ＳｉＣｐ－Ａｌ２Ｏ３）和ＳｉＣ粒子与ＳｉＣ晶须共同增强的Ａｌ２Ｏ３基复合材料（ＳｉＣｐ－ＳｉＣｗ－Ａｌ２Ｏ３）在氮气氛中进行高温氮化处理，成功地实现了这些材料的开口气孔表面裂纹的愈合。研究表明：热等静压氯化工艺可以显著提高ＳｉＣ和Ａｌ２Ｏ３陶瓷的抗弯强度，对断裂韧性也有较大的改善作用。对于热等静压烧结ＳｉＣ陶瓷，在１８５０℃和２００ＭＰａ氮气压力下氯化处理１小时后，其抗弯强度和断裂韧性分别由５８２ＭＰａ和５．７ＭＰａ·ｍ１／２提高到９０７ＭＰａ和８．４ＭＰａ·ｍ１／２；对于热压烧结的ＳｉＣｐ－Ａｌ２Ｏ３复相陶瓷和ＳｉＣｐ－ＳｉＣｗ－Ａｌ２Ｏ３复合材料，在１７００℃和１５０ＭＰａ氮气压力下氮化处理１小时后，其室温抗弯强度分别由４６０和７０５ＭＰａ提高到８９５和１０３３ＭＰａ。     

晶内型Al2O3—SiC纳米复合陶瓷的制备

研究了沉淀法制备Ａｌ２Ｏ３－ＳｉＣ纳米复合陶瓷的工艺过程，利用Ａｌ２Ｏ３从γ相到α相的蠕虫状生长过程，使大部分纳米ＳｉＣ颗粒位于Ａｌ２Ｏ３晶粒内，用沉淀法制得的、含有５ｖｏｌ％ＳｉＣ的Ａｌ２Ｏ３－ＳｉＣ纳米复合陶瓷，其强度为４６７ＭＰａ，韧性为４．７ＭＰａ．ｍ＾１／２，与一般的Ａｌ２Ｏ３陶瓷相比有较大的提高，显示了沉淀法制备Ａｌ２Ｏ３－ＳｉＣ纳米复合陶瓷的优点。     

K_2NbOF_5－MF_3系玻璃的结构及电性质

研制了Ｋ＿２ＮｂＯＦ＿５－ＭＦ＿３（Ｍ＝Ａｌ、Ｇａ）新体系氟化物玻璃，测定了玻璃的特征温度、Ｒａｍａｎ光谱和电导率，玻璃中Ｎｂ￣（５＋）、Ａｌ￣（３＋）、Ｇａ￣（５＋）分别以ＮｂＯＦ、ＡＩＦ、ＧａＦ八面体形式存在，玻璃的电导率随ＡｌＦ＿３含量的增加而增加，ＡｌＦ＿３含量达到３０ｍｏｌ％时，Ａｌ￣（３＋）除ＡＩＦ八面体外，还有ＡｌＦ四面体结构出现，同时电导率降低，Ｆ￣－阴离子是主要的导电离子，７５Ｋ＿２ＮｂＯＦ＿５·２５ＡｌＦ＿３玻璃的电导率在１９６℃时，σ＝１．０２×１０￣（－２）Ｓ·ｃｍ￣（－１）。     

冷却速度和添加剂对SiO2—Al2O3—CaO（MgO—Fe2O3—Na2O）系玻璃分相的影响

运用ＸＲＤ，ＳＥＭ，ＤＴＡ和化学分析等手段研究了不同冷却速度及添加剂对ＳｉＯ２－Ａｌ２Ｏ３－ＣａＯ（ＭｇＯ－Ｆｅ２Ｏ３－Ｎａ２Ｏ）系玻璃分相及性能的影响，结果发现不同冷却速度处理对玻璃的分相有明显影响，使玻璃呈不同颜色其中冷却速度为１５℃＝ｍｉｎ处理得到玻璃其抗折强度高于６００℃退火玻璃。     

凝胶注模Si3N4陶瓷的力学性能与显微结构

凝胶注模成型工艺是一种重要的原位凝固成型技术,它能有效地提高材料的可靠性以及降低复杂形状陶瓷部件的制造成本。本工作在Si     

Density functional study of silane adsorption onto Si(100) surface

Total energy pseudopotential calculations based on norm-conserving optimized pseudopotential and density functional theory (DFT) with generalized gradient approximation (GGA) have been used to study the possible pathway and corresponding energy barrier for the initial dissociative adsorption of silane (SiH₄) onto Si(100)-(2×2) surface leading to the formation of SiH₃ and H adsorbed on Si(100)-(2×2) i.e. Si(100)-(2×2)(SiH₃:H). Our calculated results found that the formation of Si(100)-(2×2)(SiH₃:H) after the SiH₄ initial adsorption onto Si(100)-(2×2) surface is energetically favorable. Also the energy barrier, which is calculated to be around 0.72 eV (GGA), occurs due to the elongation of Si–H within SiH₄ accompanying the unbuckling of the buckled Si=Si dimer on Si(100)-(2×2) surface. Finally, the reactive sticking coefficient for SiH₄ on Si(100)-(2×2) is calculated to be around 3×10⁻⁶.     

Squeeze cast aluminium reinforced with mild steel inserts

The bonding of a mild steel insert to an Al-7Si alloy during squeeze casting has been studied for a range of processing conditions. Assessment of the mild steel/Al-7Si alloy interface shear strength has been made with a push-out test, and the results have been correlated with microstructural observations and residual stress calculations. Uncoated inserts do not exhibit any significant reaction with Al-7Si because of rapid cooling of the melt during squeeze casting, giving a low interface shear strength of 30 MPa. Preheating the inserts to 900°C slightly improves the interface shear strength to 45 MPa, but reaction between the steel and Al-7Si is prevented by the formation of an Fe₃O₄ magnetite layer on the steel surface. Inserts hot-dipped in molten Al-10Fe before squeeze casting have a much greater interface shear strength of 110 MPa, with failure in the Al-7Si matrix rather than at the steel/Al-7Si interface. Inserts vacuum plasma spray coated with titanium have the greatest interface shear strength of 130 MPa, without any interface reaction, because of mechanical keying of the rough splat-quenched titanium surface combined with high residual stresses in the Al-7Si matrix.     

医用NiTi合金表面溶胶-凝胶法制备TiO2-SiO2薄膜

采用溶胶－凝胶法在ＮｉＴｉ形状记忆合金表面制备了ＴｉＯ_２－ＳｉＯ_２复合薄膜,在提高医用ＮｉＴｉ合金的抗腐蚀性方面,收到了显著的效果．运用电化学方法对不同组成的ＴｉＯ_２－ＳｉＯ_２薄膜在模拟体液中的腐蚀行为进行了研究,结果表明,随薄膜中 Ｔｉ／Ｓｉ比的增加,ＴｉＯ_２－ＳｉＯ_２薄膜的抗腐蚀性增强．划痕试验表明 ＴｉＯ_２－ＳｉＯ_２（Ｔｉ／Ｓｉ＝４：１）膜与ＮｉＴｉ合金基体具有较高的界面结合强度．用原子力显微镜（ＡＦＭ）对ＴｉＯ_２－ＳｉＯ_２薄膜的表面形貌及表面粗糙度进行观察和分析,解释并讨论了ＴｉＯ_２－ＳｉＯ_２薄膜的配方组成与其抗腐蚀性的关系,ＳｉＯ_２含量较少时,薄膜结构致密,膜层均匀平滑,且膜基结合力好,作为医用ＮｉＴｉ合金的表面保护层,可以使其耐腐蚀性有显著提高．     

Characterization of charge collection in CdTe and CZT using the transient current technique

The charge collection properties of Cadmium–Telluride (CdTe) and Cadmium–Zinc–Telluride (CZT) in comparison with Silicon (Si) are presented using the transient-current technique (TCT) where the current pulses are generated by -particles emitted from an ²⁴¹Am source. From the recorded current pulse shapes, the charge collection efficiency, the charge carrier mobility and the electric field distribution inside the detectors are extracted. In particular, the signals of the compound semiconductors CdTe and CZT are interpreted with respect to the build-up of space–charges in the sensor volume and the subsequent deformation of the electric field. As high-quality CdTe and CZT samples are now commercially available, the knowledge of these material characteristics is of outmost importance for the application of CdTe and CZT in X-ray imaging.

In addition, the paper describes the influence of Ohmic and Schottky contacts on the current pulses in CdTe as well as the effects of polarization, i.e. the time-dependent degradation of the detector signals due to the accumulation of fixed charges within the sensor.     

Effect of chromate conversion coatings with and without poly(acrylic acid) on the press formability, shearing properties and durability of galvanized steel laminates using poly(vinyl butyral) as core material

A sandwiched type of electrogalvanized (EG) steel sheets bonded with poly(vinyl butyral) (PVB) was used to study the effect of chromate conversion coating on the interfacial bonding and bending formability of the laminate. It was found that a proper chromium passivation on the steel surface enhanced both initial tensile shearing strength (TSS) and the joint durability in the corrosive environment. The greatest TSS, i.e. 17.8 MPa, was measured for the chromated steel sheet with chromium content ranging 0.040–0.055 g/m². A good correlation between the TSS and the bending formability of the laminate was obtained. Poly(acrylic acid) (PAA) was also added in the chromate solutions and the complex conversion coating exhibited an improvement on the shearing properties of the EG steel sandwiches. The effect of PAA incorporated in the chromate coating on adhesion was dependent upon its concentration and molecular weight. The greatest TSS, i.e. 24.0 MPa, was measured by adding a proper amount of PAA with MW = 380,000 g/mol, approximately 8 wt%, in the chromate solution for EG surface coating. The possible mechanism of the enhancement of interfacial properties due to the incorporation of PAA will be discussed.     

The surface of carbon fibres continuously treated by cold plasma

The surface of carbon fibres prepared from polyacrylonitrile (PAN) precursor have been continuously treated by means of a cold plasma. The interlaminar shear strength of carbon fibre reinforced epoxy composites containing fibres so treated was increased from about 60 MPa to 100 MPa. There are four possible mechanisms for this increase:

1. (1) Higher reactivity between fibre surface and matrix as a result of an increase of

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groups on the fibre surface.

2. (2) The surface constitution was changed by the plasma treatment so as to improve the wetting properties of fibre surface. The contact angle θ between water and the carbon fibre was decreased from 75° to 61°.

3. (3) Electron micrographs of the surface of carbon fibre show that the surface striations and surface roughness were changed increasingly on fibre surfaces after plasma etching. This increases the interfacial adhesion and the effect of mechanical interlocking.

4. (4) The strength of the carbon fibre was decreased very little (about 1·6%) by this surface treatment method.

Analysis of fracture morphology by scanning electron microscopy (SEM) indicates that debonding and fibre pull-out between fibre and matrix do not occur in the treated carbon fibre reinforced epoxy composite. These results all show that adhesion between fibre and matrix is very strong. In addition, the plasma treatment technology is very simple and the cost is low. This treatment process produces no environmental pollution and has promising future for engineering applications.     

真空热压烧结制备Fe_3Si基金属间化合物

采用真空热压烧结工艺直接烧结Fe、Si混合粉末,制备了Fe3Si金属间化合物。研究了热压烧结时间对烧结产物微观结构、硬度及致密度的影响。结果表明,经950℃、22MPa热压烧结0.5～4h均可得到高度有序的Fe3Si块体,且随烧结时间的延长,烧结产物中Fe3Si的含量有所增加,但当烧结时间长于2h,Fe3Si的有序度有所降低。同时烧结产物的硬度和密度也有同样的变化规律,其中烧结时间2h时烧结产物具有最佳硬度和密度,分别为90.7HRC和4.62g/m3。     

稀释剂量对反应烧结Si_3N_4陶瓷结构和性能的影响

以工业Si粉为原料,α-Si3N4粉为稀释剂,聚乙烯醇为粘结剂,采用反应烧结工艺制备了Si3N4陶瓷。研究了稀释剂量对反应烧结Si3N4陶瓷的体积密度、开气孔率、相组成、微结构、弯曲强度和抗热震性的影响。结果表明,随稀释剂量的增加,Si3N4陶瓷的体积密度从2.27g/cm3降至2.04g/cm3,开气孔率从23%升至33.8%。Si3N4陶瓷由α-Si3N4、β-Si3N4和少量单质Si组成。Si3N4主要以针状晶形式存在,残留Si呈不规则块体。随着稀释剂量的增加,4组Si3N4陶瓷的三点抗弯强度分别为119MPa、112MPa、146MPa和113MPa;经50次800℃至室温空冷热震后,其强度保持率分别为81.5%、90.2%、87%和88.5%,表现出较好的抗热震性。     

SiO2-Si3N4复合材料的力学性能及其增韧机理

采用热压工艺制备了ＳｉＯ２－Ｓｉ３Ｎ４复合材料，其抗弯强度和断裂韧性达到１４３ＭＰａ和１．７ＭＰａ．ｍ＾１／２，比基体ＳｉＯ２材料分别提高１０７％和７０％，复合材料改善是由于高弹性模量的Ｓｉ３Ｎ４引入以及ＳｉＯ２和Ｓｉ３Ｎ４热膨胀系数不匹配导致的残余应力。