直接冷却半连续铸造铝合金圆锭水冷边界试验研究

通过试验方法测定直接冷却半连续铸造铝合金圆锭凝固过程的温度变化曲线,利用逆向法计算出铸锭表面换热系数,并进行理论分析.研究表明,水冷换热系数与铸锭表面温度的关系曲线可作为直接冷却半连续铸造过程数值模拟的水冷边界条件.     

慢加载时拉伸速率与铸铝合金的力学性能

在研究了慢加载条件下拉伸速率与球墨铸铁间力学性能的关系后，将试验对象扩展到铸铝合金，结果证实，在ε＝10^-1-10^-4s^-1范围内，铸铝合金的力学性胡亦随拉伸速率的逐渐减慢呈峰状变化，即先逐渐增加，到某一最大后又逐渐降低，曲线的走向与球墨铸铁的相应曲线极为相似。     

金刚石粉/环氧树脂胶粘剂的导热性能

以金刚石粉、环氧树脂E-20、甲醚化氨基树脂、助剂制备成导热绝缘胶粘剂,在130℃保温30 min,210℃保温10 min固化.胶粘剂固化后导热系数随金刚石粉体积含量增加先增大后减少,存在一个极大值.相同金刚石粉体积含量下,较大粒径的金刚石粉之间能形成更好的物理接触,有利于导热性能的提高.用常用经验导热模型拟合胶粘剂固化后的导热系数结果表明:在金刚石粉体积分数小于16.6%时,Maxwell方程能较好拟合胶粘剂的导热系数;体积分数为16.6%～44.7%时,Bruggeman和Agari模型能较好地描述胶粘剂的导热系数.     

Ablation properties of C/C composites with various needled preforms prepared by isothermal chemical vapor infiltration

The ablation properties of C/C composites with four different needled preforms prepared by isothermal chemical vapor infiltration (ICVI),which are super-thin mat lay-up,0°/90° weftless fabric lay-up,0°/45° weftless fabric lay-up and 0°/45° twill fabric lay-up,were quantitatively evaluated by performing the ablation tests with an engine torch.And their ablation discrepancies were analyzed according to the surface characteristic,porosity and thermal diffusivity.The results show that the 0°/45° weftless composite has a flat eroded surface with no obvious macroscopic pits.Its thickness and mass erosion rates are decreased by about 46.8% and 34.8%,25.0% and 27.5%,and 17.5% and 19.4% compared with those of the mat,the 0°/90° weftless and the 0°/45° twill composites,respectively.The ablation properties are mainly controlled by the thermo-chemical effect (oxidation),and a little by the thermo-mechanical effect (mechanical denudation).The needling fiber bundles play an important role in accelerating the ablation process and resulting in the heterogeneous ablation.     

铝基APCVD沉积SiOx膜层的光学性能研究

采用低温常压化学气相沉积（APCVD）的方法在铝基底上制备硅氧化物陶瓷膜层。采用XPS、
XRD、HRTEM、UV-VAS和NIRS等技术分析膜层的成分、结构组织和形貌特征，并测试了膜层的光学吸收性能
。研究结果表明，SiOx中的硅氧原子比为1∶1.60～1∶1.75，硅氧化物陶瓷膜层大部分为非晶态组织，包
含少量局部有序区域。SiOx陶瓷膜层沉积在铝基上后具有很高的紫外可见光吸收率和较高的近红外光吸收
率，产生机制是硅氧化物陶瓷膜层中氧空位存在局域电子态，电子吸收能量产生能级跃迁。     

Effects of parameters on formation and microstructure of surface composite layer prepared by lost foam casting technique

Surface composite layer was fabricated on the AZ91D substrate using the lost foam casting (LFC) process. The pre-coating layer reacted with melt substrate and formed the composite layer, and the coating was mainly consist of alloying aluminum powder and low-temperature glass powder (PbO-ZnO-Na2O). The vacuum degree, pouring temperature, mold filling process of melt, and pre-coating thickness played an important role during the formation process of composite layer. The results show that surface morphology of composite layer can be divided into three categories: alloying effect of bad and good ceramic layer, alloying effect of good and bad ceramic layer, composite layer of good quality. The main reason for bad alloying layer is that alloying pre-coating thickness is so thin that it is scoured easily and involved in the melt, in addition, it is difficult for melt to infiltrate into the alloying coating owing to the surface tension of coating when the vacuum degree is excessively low. Bad ceramic layer is because of somewhat lower pouring temperature and the thicker alloying coating, due to the absorption of heat from the melt, making low temperature glass powder pre-coating layer fuse inadequate. Thus, to get good quality composite layer, the process conditions must be appropriate, the result shows that the optimum process parameters are as follows: at a pouring temperature of 800 ℃, vacuum degree of -0.06 MPa, alloying pre-coating thickness of 0.4 mm, and low glass powder pre-coating layer thickness of 1 mm.     

无机胶粉料聚苯乙烯颗粒保温隔热材料的研究

介绍了一种以聚苯乙烯颗粒，粉煤灰等为主要原材料制备保温隔热材料的方法，重点研究了保温隔热材料的组成与粘结强度，干燥容量，导热系数，干燥收缩率等的关系；探讨了无机胶粉料聚苯乙烯颗粒保温隔热材料的保温隔热机理。     

Thermal stability and oil absorption of aluminum hydroxide treated by dry modification with phosphoric acid

The dry modification of aluminum hydroxide powders with phosphoric acid and the effects of modification of technological conditions on thermal stability, morphology and oil absorption of aluminum hydroxide powders were investigated. The results show that the increase of mass ratio of phosphoric acid to aluminum hydroxide, the decrease of mass concentration of phosphoric acid and prolongation of mixing time are favorable to the improvement of thermal stability of aluminum hydroxide; when the mass ratio of phosphoric acid to aluminum hydroxide is 5:100, the mass concentration of phosphoric acid is 200 g/L and the mixing time is 10 min, the initial temperature of loss of crystal water in aluminum hydroxide rises from about 192.10 to 208.66 ℃, but the dry modification results in the appearance of agglomeration and macro-aggregate in the modified powders, and the oil absorption of modified powders becomes higher than that of original aluminum hydroxide.     

钛酸钾晶须改性偏高岭土基多孔地质聚合物的制备与性能

为提高多孔地质聚合物的力学强度和隔热性能,分别以双氧水（H2O2）和十二烷基硫酸钠（SDS）为发泡剂和稳泡剂,采用化学发泡法制备了由钛酸钾晶须改性的偏高岭土基多孔地质聚合物材料,对其进行了微观结构表征及性能测试。结果表明,当发泡剂和稳泡剂质量分数分别为2.0%和1.5%时,孔结构分布均匀,总孔隙率最高可达51.6%,平均孔径为0.87 mm,其抗压强度为3.63 MPa;随着钛酸钾晶须质量分数从0.0%增至10.0%时,其最高抗压强度可达4.11 MPa。在钛酸钾晶须质量分数为20%时,其最低导热系数可达0.048 W/（m?K）,相比于空白样,抗压强度提高了13.22%,导热系数降低了80.80%。钛酸钾晶须的引入可以明显提高多孔地质聚合物的抗压强度和隔热性能。     

Microstructural and mechanical properties of A1-4.5wt% Cu rein- forced with alumina nanoparticles by stir casting method

The microstructure and mechanical properties of A1-4.5wt% Cu Mloy reinforced with different volume fractions （1.5vo1%, 3vo1%, and 5vo1%） of alumina nanoparticles, fabricated using stir casting method, were investigated. CMculated amounts of alumina nanoparticles （about ~50 nm in size） were ball-milled with aluminum powders in a planetary ball mill for 5 h, and then the packets of milled powders were incorporated into molten Al-4.5wt% Cu alloy. Microstructural studies of the nanocomposites reveal a uniform distribution of alumina nanoparticles in the A1-4.5wt% Cu matrix. The results indicate an outstanding improvement in compression strength and hardness due to the effect of nanoparticle addition. The aging behavior of the composite is also evaluated, indicating that the addition of alumina nanoparticles can accelerate the aging process of the Mloy, resulting in higher peak hardness values.