Silicon nitride (Si3N4) powders were synthesized with silica sol, urea and carbon black by ammono sol2gel processing. Urea was dissolved in water and mixed homogeneously with silica sol. Ammonolysis of the aqueous solution could form a precursor, which was then mixed with carbon black and nitrided at 1300～1600℃under a flowing N2 atmosphere. The precursor and final powder were characterized by X-ray diffractometry, infrared spectroscopy and transmission electron microscopy. Results showed that Si3N4 powders with a size of 50～80nm and a content of more than 37% nitrogen can be obtained from the precursor annealed at 1500℃under a N2 flow of 3L/min for 2h. Effects of ammonolysis and synthesizing conditions on the final products were investigated.

Al2O3陶瓷在800℃以上高温下的磨损明显减小，在摩擦表面形成了由极细晶粒构成的表面层。为了探讨这种表面层的形成机理，研究了Al2O3/Al2O3摩擦副在800～1200℃下于干摩擦时的塑性变形与再结晶，且用表面层厚度和晶粒大小来表征。表面层厚度和再结晶粒子尺寸均取决于试验温度、表观接触压力和滑动速度。根据对应变速率和摩擦表面温度的测算，发现再结晶粒子尺寸与Zener2Hollomon常数Z的对数存在良好的线性关系，说明Al2O3陶瓷在高温磨损中的再结晶属动态再结晶。由塑性变形引发的动态再结晶是导致表面层形成的主要机理。

研究了Al2O3陶瓷从室温至1200℃在干摩擦条件下的高温摩擦磨损行为。结果表明：在600℃以后的摩擦磨损随温度上升而逐渐减小。在1200℃的摩擦系数仅为室温的60%，磨损则降低了两个数量级。表现出良好的高温自润滑特征。在不同温度下，存在三种显著不同的磨损机理。从室温至600℃，主要是磨粒磨损和微断裂，磨损随温度上升而略有增加。在600～1000℃，磨损机理逐渐由脆性断裂过渡到塑性变形和再结晶，在表面形成一个厚度为5～10μm的、类似于纳米材料结构的特殊表面层。随着这种特殊表面层的形成。磨损显著下降。在1200℃，摩擦表面由塑性变形发展到软化状态，出现流体动力润滑，使摩擦磨损进一步降低。

研究了碳化硅陶瓷在空气和真空环境中从室温至1200℃的摩擦磨损特性。摩擦系数对温度的依存性取决于接触压力和气氛。当接触压力为1.2MPa时，摩擦系数几乎与温度无关，但在空气中的摩擦系数明显大于在真空中的。比磨损率也与温度、气氛和接触压力密切相关。实验中观察到了三种磨损模式，其比磨损率分别随温度的升高而呈现增加、基本不变和减少的趋势。在高温和0.2MPa接触压力下获得了低的磨损，但在高温和0.4MPa接触压力下的磨损却显著增大。表面剥离和塑性变形是碳化硅在高温下的主要磨损机理。

本文对原位反应合成的C-SiC-TiC-TiB2复合材料在600-1200℃空气中的抗氧化性进行了研究。在不同材料组成和试验温度下，试样分别出现氧化增重和失重，这主要取决于碳相和陶瓷相的氧化速率及氧化层的结构特征。在600℃该材料几乎不被氧化；800℃时，TiB2被优先氧化，形成B2O3液相；在1000℃以上，B2O3与SiO2生成硼硅酸盐玻璃，形成一致密氧化层。氧化过程中液相的出现和致密氧化层的形成显著降低了氧化速率，使材料进入钝氧化，从而大幅度地提高了该材料的抗氧化能力。

以Ti，Al和C粉末为原料，采用接触反应法制备原位TiC颗粒增强的铸造Al2Cu复合材料，研究了反应温度对反应产物的影响，探讨了TiC颗粒的形成机制。结果表明，随着反应温度的升高，副产物TiAl3和Al4C3生成的可能性减小；当反应温度为900℃时，反应副产物全部转变为TiC，且原位反应生成0.5～1.5μm的TiC颗粒均布于α2Al基体中；TiC的加入能显著提高基体的强度，特别是高温强度，但使其延伸率有所下降。

以硅溶胶、尿素和炭黑为原料，经氨解溶胶-凝胶、碳热还原法合成了纳米Si3N4-SiC复合粉末。通过在硅溶胶中引入Y（NO3）3，合成了Si3N4-SiC-Y2O3超细复合粉末。Y2O3的加入有助于降低Si3N4-SiC的合成温度。采用XPS和XRD分析复合粉末中Y的存在状态表明：一部分Y固溶在Si3N4-SiC中，另有一部分以Y2O3形式存在。Si3N4-SiC-Y2O3复合粉末的烧结性能良好。

The adsorption of poly(acrylic acid) (PAA) in aqueous suspension onto the surface of TiO2 nanoparticles was investigated. FTIR spectroscopic data provided evidence in support of hydrogen bonding and chemical interaction in the case of the PAA–TiO2 system. Adsorption isotherms demonstrated that part of the PAA initially added to the suspension was adsorbed onto the TiO2 surface, after which there was a gradual attainment of an adsorption plateau. The adsorption density of PAA was found to increase with an increase of PAA molecular weight, while it decreased with an increase of pH. The thickness of the PAA adsorption layer was calculated based on measurements of suspension viscosities in the absence and presence of PAA. It was shown that the thickness of the adsorption layer increased with the increase of pH, PAA molecular weight, and its concentration. The surface charge density, the diffuse charge density, and the zeta potential of TiO2 varied distinctly after PAA adsorption. The shift of pHiep toward a lower pH value was observed in the presence of PAA. PAA was found to stabilize the suspension of TiO2 nanoparticles through electrosteric repulsion. The influence of factors such as PAA molecular weight and its concentration on the colloidal stability of the aqueous suspension was also investigated.

The thermal degradation behaviour of polyacrylate and its zinc oxide composites were investigated by differential scanning calorimetry (DSC), thermogravimetry (TG) and Fourier transform infrared spectroscopy (FTIR). Reaction mechanisms of polymer degradation with and without ZnO particles were obtained. Filler-free polyacrylate exhibited one DSC peak, indicating that the polymer was degraded with only one stage of weight loss. Polyacrylate/ZnO composites underwent two minor weight losses as well as the major weight loss. ZnO stabilized or destabilized the polymer molecules according to the temperature region. Two mechanisms were proposed for the change of thermal properties of the nanocomposite. An increase of the stabilization or destabilization effect of ZnO nanoparticles was found in the nanocomposite with a higher content of the inorganic phase. Compared to micron ZnO particles, ZnO nanoparticles exhibited a greater effect due to their high specific area giving more sites for interactions. In addition, kinetics of thermal degradation of filler-free polyacrylate and polyacrylate/ZnO composite were quantitatively obtained by means of non-isothermal weight loss data analysis.

The oxidation kinetics and mechanism of gradient SiC coating/3D carbon fiber braid (coated braid, CB) in static air were studied through isothermal oxidation-weight loss, non-isothermal thermogravimetric (TG) and differential thermogravimetric (DTG) also. The results showed that the oxidation process of CB in isothermal condition was reaction-controlled in the first step and, gas diffusion and reaction-controlled in the second step. In non-isothermal condition, the characteristic of oxidation process was self-catalytic. The oxidation mechanism was one-dimensional diffusion. The kinetic parameters were: log A (min-1)=10.12 and Ea (kJ mol-1)=224.96.