提高自蔓延高温合成陶瓷内衬复合钢管性能的措施

离心铸造技术和自蔓延高温合成技术结合在一起而发展起来的离心自蔓延高温合成技术用于制造复合钢管 ,具有工艺与设备简单、生产率高、节能和成本低等特点 ,为陶瓷内衬复合钢管的生产开辟了新的途径。该复合钢管的性能决定于陶瓷层的性能 ,从提高陶瓷层致密度和结合强度、降低裂纹率、提高耐腐蚀性等方面 ,综述了提高其性能的途径 ,展望了广阔的应用前景     

High-Strength Porous Alumina Ceramics by the Pulse Electric Current Sintering Technique

High-strength porous alumina has been fabricated with a microstructure control using the pulse electric current sintering (PECS) technique. During sintering the discharge, which is assumed to take place in the voids between the particles, is thought to promote the bridging of particles by neck growth in the initial stages of sintering, leaving high porosity. The effect of dopants (MgO, 200 ppm; TiO₂, 1000 ppm) and of secondary inclusions (3 vol% 3Y-TZP) on the constrained densification and the improvement in the mechanical behavior of porous alumina ceramics has been reported. The porosity of the fabricated porous alumina was controllable between 30% and 50% depending on the sintering temperature. The flexural strength of alumina having 30% and 42% porosity showed impressive values of 250 and 177 MPa, respectively. The dominance of the preferential neck growth of grains over densification significantly improved the mechanical properties of porous alumina, besides leaving high porosity.     

Effect of Enameling on the Strength and Dynamic Fatigue of Soda–Lime–Silica Float Glass

The effect of a glass enamel coating on the strength and fatigue behavior of float glass was investigated. Commercially available enamel that was comprised of Cu₂Cr₂O₄ pigment particles in a bismuth-zinc borosilicate glass matrix was applied to a soda–lime–silica float glass via screen printing, followed by fusion at elevated temperature. Strengths of the enameled specimens were evaluated in biaxial flexure using a ring-on-ring (ROR) test geometry, and the data were analyzed using a conventional two-parameter Weibull distribution. Enameling was found to significantly degrade the strength of the float glass. There was no statistical difference in the characteristic strengths of samples enameled on the air side (66 MPa) compared with samples enameled on the tin side (61 MPa) of the float glass. Fractographic analysis revealed that the failures in the enameled float glass samples initiated at pores and pigment aggregates in the enamel, whereas failures in float glass samples initiated solely from surface flaws. Dynamic fatigue tests were performed on enameled float glass and indented float glass samples to determine the effect of the enamel on the stress corrosion behavior of the enameled components. There was no statistically significant difference between the stress corrosion exponents for the float glass and enameled float glass specimens.     

Calcium Phosphate Bioceramics with Various Porosities and Dissolution Rates

Porous bioceramics, such as hydroxyapatite (HA), tricalcium phosphate (TCP), and biphasic HA/TCP, were fabricated using the polyurethane sponge technique. The porosity of the ceramics was controlled by a multiple coating of the porous body. When a porous body was produced by a single coating, the porosity was ∼90%, and the pores were completely interconnected. When the sintered body was coated five times after the porous network had been made, the porosity decreased to 65%. As the porosity decreased, the strength increased exponentially. The TCP exhibited the highest dissolution rate in a Ringer's solution, and the HA had the lowest rate. The biphasic HA/TCP showed an intermediate dissolution rate.     

短纤维直径对橡胶复合材料性能的影响

制备了 3种具有不同直径、相同长径比及其分布的涤纶短纤维增强氯丁橡胶基复合材料。对屈服强度及伸长率、断裂强度及伸长率以及撕裂强度等力学性能的研究发现 :在相同长径比及其分布情况下 ,与传统混合法则不同的是屈服强度和伸长率不相等 ,也不是只取决于短纤维的直径 ,而是受直径和长度的共同作用 ;在相同的纤维体积分数时 ,复合材料的断裂强度基本相同 ,而断裂形变和撕裂强度随纤维直径的减小而增大     

溶胶-凝胶工艺制备ZrO2涂层对工程陶瓷表面改性的研究

采用无机盐先驱体 ,溶胶 -凝胶工艺在氧化铝基工程陶瓷上成功制备了ZrO2 涂层。用差热分析(DTA)、扫描电子显微镜 (SEM)、X射线衍射 (XRD)等分析手段对ZrO2 涂层的物相组成、表面和断面形貌进行了表征。对精磨、热处理、ZrO2 涂层试样的抗弯强度和Weibull模数进行了比较。结果表明 :ZrO2 涂层可以明显改善陶瓷的表面质量 ;涂层与基体结合紧密 ,无明显的界面层 ;涂层试样的抗弯强度和Weibull模数均比未涂层试样有明显的提高。     

流化床燃煤固硫渣混凝土的试验研究

研究了流化床燃煤固硫渣作细骨料配制混凝土及混凝土的性能。结果表明 ,固硫渣可代砂配制道路砼。     

多管程管壳式换热器管箱法兰的强度计算

多管程、高压、高温换热器管箱法兰的垫片密封问题对法兰强度的影响 ,在有关的标准规范中没有相关说明 ,设计中往往被忽略了。通过计算实例进行分析 ,可见其影响有时还比较大 ,建议通过折算进行强度计算 ,确保其安全可靠。     

普通用途防撕裂钢丝绳芯输送带的研制

介绍了普通用途防撕裂钢丝绳芯输送带的研制。主要包括纵向骨架材料的选择、横向增强层（防撕裂层）的选择、覆盖胶和芯胶及贴胶配方的设计和实际生产工艺。经过试验测试，产品性能符合HG3646－1999标准。该产品已获国家专利。     

Lyocell纤维原丝的性能对碳纤维强度的关联分析

运用灰色系统方法对新型纤维素原丝Lyocell纤维的性能与碳纤维强度之间的关系进行了关联分析，结果表明：Lyocell纤维的强度、纤度和断裂强力对碳纤维的强度有很大的影响，而对伸长和模量的影响较小。