Ceramic Engine Valves

Current trends in spark ignition engines are toward multivalve engines capable of operating at relatively high speeds to maximize performance and fuel economy at acceptable emissions levels. Structural ceramics, with their low density and good high-temperature properties, appear to offer potential as an alternative valve material to the steels, superalloys, and titanium alloys currently in use. Progress to date on materials development, component design, component performance, and engine testing indicates that silicon nitride valves will operate satisfactorily.     

黑水陶瓷调节球阀结构校核及改进

介绍了煤化工用黑水陶瓷调节球阀的使用工况和设计特点,对该阀门的结构进行校核,给出了该阀门使用中存在的问题及其解决方案,改进后的黑水陶瓷调节球阀使用状况良好。     

6105机氮化硅陶瓷气门材料及部件制备的研究

本研究采用近净尺寸等静压成型，无压烧结Ｓｉ３Ｎ４工艺成功地制备了同了６１０５紫油机Ｓｉ３Ｎ４对陶瓷气门材料及制备工艺进行了详细讨论。     

陶瓷真空过滤机应用评价

针对连续熔硫存在的问题,新上硫泡沫过滤机,采用间断+连续工艺回收硫磺.     

陶瓷艺术的定性评价体系研究

从“器”、“艺”、“人”和“论”四方面进行了陶瓷艺术的定性评价.由于陶瓷艺术是一种独特的艺术,通过对陶瓷艺术的“四元评论”,建立了综合评价体系.另外,对陶瓷艺术理论的形成和陶瓷艺术评价理论体系的形成进行了探索性研究.     

硅氮系阻燃黏胶纤维的结构与性能研究

分析了硅氮系阻燃黏胶纤维的结构与性能,探讨其阻燃机制。通过扫描电子显微镜、X射线衍射、力学性能以及极限氧指数等测试,分析了硅氮系阻燃剂含量对纤维阻燃性能、热性能和力学性能等的影响。结果表明:当阻燃剂质量分数为20%时,纤维的干态断裂强度为2.1 cN/dtex,极限氧指数为28%,在满足纺织服用需求的同时,达到国家阻燃标准,兼具安全环保与良好的阻燃性能。     

陶瓷艺术的DEA效率评价模型

通过对陶瓷艺术的影响因素和价格的关系研究及影响陶瓷艺术价格定性因素的定量化,并建立了数据包络分析效率评价模型.应用数据包络分析效率评价模型计算效率值来评价艺术陶瓷相对有效性具有较好的意义。实例说明本模型具有较好的适应性和应用性,克服了仅用预测的误差评价陶瓷艺术价格的波动性。     

传统陶瓷耐磨性能评价方法

本文介绍了现有的传统陶瓷产品耐磨性能测试方法与标准,分析了这些测试方法用于测试传统陶瓷耐磨性能的可行性和不足之处,提出可以统一有釉砖与无釉砖耐磨性能测试方法与标准。     

Fracture Toughness Evaluation of Small Thin Ceramic Specimens

A test method to evaluate the fracture toughness, K_IC, of thin, small, precracked ceramic specimens is described. The method is applicable for thin plates, wafers, self-supported layers, etc., especially when a large amount of material is not available for testing. The method consists of bonding a small, thin single-edge notched beam on one side of a metallic beam. A stress-free precrack with a square root singularity is achieved when the assembly is deformed in three-point bending.
The fracture toughness of a thin, alumina single-edge precracked beam was evaluated experimentally using this method, and compared with that obtained for similar specimens having a 0.3-mm-wide machined notch. Comparison with previously reported fracture toughness values suggests that even a very sharp machined notch overestimates the evaluated fracture toughness.     

零泄漏工程蝶阀及高性能球阀的结构特性

在流体输送过程中,作为启闭与调节流量的阀门是必不可少的,蝶阀与球阀因其具有调节及密封性能好、阻力小、启闭迅速等诸多优点,尤其是蝶阀尺寸紧凑、重量轻,占有空间小的优势,已逐步取代传统的闸阀和截止阀,成为配管设计中优先考虑的阀型,在国外工程装置中的采用也越来越多。为此,国内外的阀门厂均十分重视其设计开发工作,争取生产出各种性能优异价格低廉的新产品以取胜于同行,在欧洲市场中尤以西班牙生产的TTV专用工程蝶阀及PEKOS球阀正是其中的姣姣者,在国内某进口工程项目中选用近百台TTV蝶阀用于流体输送及排放。现重点介绍TTV专用蝶阀：     

氮化硅陶瓷覆铜基板制备及可靠性评估

氮化硅陶瓷覆铜基板优异的高可靠性使其成为高铁、电动汽车等领域功率模块最有前途的基板材料之一,目前只有日本厂商具备量产能力,国内进口困难,阻碍了相关产业的发展.采用气压烧结实现了高性能氮化硅陶瓷基板的制备,并通过活性金属钎焊工艺获得了氮化硅陶瓷覆铜基板.氮化硅陶瓷的弯曲强度800 MPa,断裂韧性8.0 MPa·m1/2,热导率90 W/(m·K),交流击穿强度40 kV/mm和体积电阻率3.7×1014Ω·cm;氮化硅陶瓷覆铜基板的剥离强度达到130 N/cm.在-45～150℃高低温循环冲击下,氮化硅陶瓷覆铜基板的冲击次数分别达到氮化铝和氧化铝覆铜基板的10倍和100倍;在铜厚0.32 mm/0.25 mm冲击次数达5000次和铜厚0.5 mm/0.5 mm冲击次数达1000次的情况下,样品均完好无损;在铜厚0.8 mm/0.8 mm冲击次数达500次时,样品仍未产生微裂纹等缺陷,这与铜厚0.32 mm/0.25 mm时氮化铝覆铜基板的循环次数相当;氮化硅陶瓷覆铜基板的可靠性明显优于现有产品.     

A Simple Test for Thermomechanical Evaluation of Ceramic Fibers

A simple bend stress relaxation (BSR) test has been developed to measure the creep-related deformation properties of ceramic fibers and whiskers. The test was applied to a variety of commercial and developmental Si-based fibers to demonstrate test capabilities and to qualitatively evaluate the relative creep resistance of the fibers at 1200° and 1400°C. The implications of these results and the advantages of the BSR test over typical tensile creep tests are dicussed.     

Evaluation of Ceramic Matrix Composites by Thermal Diffusivity Imaging

Because of the complex structural design and multiple processing steps, ceramic matrix composites (CMCs) typically contain a variety of flaws distributed throughout the volume. These flaws need to be detected and characterized because they are detrimental to CMC material properties. Thermal diffusivity imaging is a nondestructive evaluation method that can quantitatively determine the thermal property of a CMC component. Thermal diffusivity is an intrinsic material property that not only depends on the material constituents but also on the micro- and macrostructure of the CMC component. This paper investigates fundamental theories for thermal diffusivity measurement using pulsed thermal imaging from two- and one-sided setups. The variation of thermal diffusivity is examined for two types of flaws, voids and cracks, that are commonly present within CMCs. The sensitivity of thermal imaging to detect small and large flaws is analyzed and evaluated with measured thermal diffusivity data. In addition, analysis of fracture theories for the mechanical and thermal properties of materials with distributed microcracks has identified that thermal diffusivity may be used to determine the degradation of mechanical properties and, therefore, to predict the remaining life of a CMC component. Preliminary results for correlating thermal and mechanical properties are discussed.     

陶瓷原料质量评价方法研究

陶瓷原料质量受诸多因素影响,合适的原料是生产优质陶瓷产品的保证。本文通过一系列的应用研究,探讨了陶瓷原料的质量评价方法,以保证选取适当的陶瓷原料,为生产出高质量的陶瓷产品奠定基础。     

Quantitative Evaluation of Void Distributions within a Plasma-Sprayed Ceramic

The size–shape distribution of voids, which includes cracks and pores, was determined using quantitative stereological analysis. The analysis was performed on a water-stabilized plasma-spray-formed Al₂O₃–13 wt% TiO₂. The individual voids were assumed to have an oblate spheroidal shape, which could simulate shapes ranging from spherical pores to cracks. The cracks were generally intralamellar or translamellar, and the pores were interlamellar. The information obtained from two-dimensional plane sections was unfolded to three-dimensional information using stereological analysis. The quantitative information of voids was acquired in terms of shape and size.     

Analytical Evaluation of Interfacial Shear Strength for Fiber-Reinforced Ceramic Composites

A methodology is described to evaluate the shear strength at the fiber–coating interface. Stress analyses are performed for the following system: a fiber with a uniform coating in its central portion which is subjected to an axial tensile stress through its bare ends. The results show that the axial tensile stress in the coating decreases with the increase in the thickness of the coating and that the interfacial shear stress exhibits the opposite trend. Hence, a critical thickness of the coating can be defined depending on the properties of the material, such that when the coating thickness is less than the critical value, failure of the composites initiates from segmentation of the coating during tensile loading. Conversely, when the coating thickness is greater than the critical value, debonding of the interface occurs. Furthermore, the interfacial shear strength can be related to this critical thickness and the tensile strength of the coating.     

可监测阀板开关及阀板下压力的井筒压力控制阀

井筒压力控制阀有阀体、液控管线、压力测量与监控系统、液控管线保护卡、地面控制柜等组成。井筒压力控制阀与欠平衡钻井作业设备配套可实现钻井、完井、测井等全过程欠平衡钻井施工作业。本文介绍了井筒压力控制阀技术研究工作及现场应用情况。     

新型自封带旁通阀回油过滤器基本模型介绍

针对箱侧、箱底回油过滤器的特点,提出一种较传统结构更简单、使用起来更方便的结构模型。