陶瓷刀具切削区温度场的计算机模拟

在切削金属过程中所消耗的能量几乎９０％以上都转化为热，致使工件，切屑和刀具的温度都上升，其中刀具的温升与切削机理及切削参数密切相关，并且直接影响刀具磨损及其全用寿命。为了研究陶瓷刀具切削温度分布对其磨损规律和机理的影响，根据传热理论建立了数学模型，用计算机模拟编制出陶瓷刀具切削区温度场计算的专业软件，可以得出不同陶瓷料刀具在不同切削条件下切步同工件材料过程中的温度分布曲线图，而且实际测量值与模拟值     

氮化硅陶瓷平板振动模态参数的研究

本文采用压电陶瓷片测振技术,试验分析了氮化硅陶瓷平板的固有频率及模态阻尼比,试验结果与有限元计算结果比较吻合。本文还对氮化硅陶瓷平板与普通钢平板做了对比试验,结果表明氮化硅陶瓷平板的固有频率及模态阻尼比都较高。     

陶瓷阻力曲线测定的新方法——断裂栅法

将零厚度单向试件栅刻蚀工艺应用于晶须增韧氮化硅陶瓷基复合材料表面，通过记录试件所在桥路的输出电压值，可得到随载荷不断增大裂纹逐渐向前扩展过程中每一时刻的裂尖位置和裂纹长度，从而得到该种材料的阻力曲线。     

Micromechanics of residual stress and texture development due to poling in polycrystalline ferroelectric ceramics

This paper presents micromechanics based analysis of elastic strain and changes in the texture of poled polycrystalline ferroelectric PZT ceramics for direct comparison with synchrotron X-ray measurements. The grains are modelled as spherical inclusions, to which transformation strains are assigned depending on the fractions of different ferroelectric domains. Eshelby's inclusion problem with the classical self-consistent method is applied to evaluate the elastic state of the grains. In particular, the elongation due to lattice elastic strain is calculated as a function of inclination Ψ relative to the polar axis. The ratio of diffraction peak intensities, corresponding to the domain fractions, is also expressed as a function of Ψ. This analysis identifies the special character of the reflection, for which the lattice strain along in the stress free state is independent of ferroelectric domain population and hence unaffected by poling. The elongation due to the lattice strain parallel to and peak intensity ratio are expressed in terms of the overall macroscopic strain of a poled specimen, each having a dependence.     

非均匀铁弹畴变对离面极化压电陶瓷应力强度因子的影响研究

基于文献中报道的试验结果，本文考虑非均匀的畴变过程区，它包含一个位于中心的饱和区和环绕饱和区的渐变区．为了描述外加应力引起的部分铁弹畴变，本文采用一个显式的基于最小能量原理的非均匀畴变准则．考虑离面极化的压电陶瓷，假设其初始极化矢量平行于离面方向．畴变后的电畴位于面内，具体方位由最大释放功来确定．基于非均匀畴变准则，本文给出了裂尖处非均匀畴变区几何及畴变体积分数的分布．并在静止裂纹和稳态扩展裂纹两种特殊情况下计算了铁弹畴变对裂尖处应力强度因子的影响．结果表明：(1) 静止裂纹尖端处的畴变减小了材料的起裂强度；(2) 准静态稳态裂纹附近的畴变增加了材料的断裂强度．且理论预测的R曲线渐近值与试验结果定量吻合．     

Radiative heat transfer augmentation of natural gas flames in radiant tube burners with porous ceramic inserts

Experiments were conducted using porous ceramic inserts to enhance the radiative heat transfer from natural gas flames in a straight-through radiant tube burner. The performance of the radiant tube burner with partially stabilized zirconia and silicon carbide inserts is compared to a baseline case of no inserts at three levels of combustion air preheat. Spectral intensities, temperatures within the radiant tube burner, tube wall temperatures, and exhaust temperatures were measured to determine the effectiveness of the enhanced heat transfer due to the inserts. Exhaust emission constituents were also measured to determine the effect that the inserts have on exhaust products. NO_x emissions are reduced by up to 30% with the inserts. The silicon carbide inserts have higher spectral intensities and total radiative energy transfer than partially stabilized zirconia inserts. Both inserts have enhanced radiant heat transfer compared to the no-insert configuration, with the radiative enhancement due to inserts as great as five times that of the no-insert configuration. The net result is increased tube wall temperatures and decreased exhaust temperatures with the ceramic inserts.     

Al_2O_3 基陶瓷摩阻材料的摩擦磨损特性

在ＭＧ－２００磨损试验机上，对以Ａｌ２Ｏ３为基体，分别添加固体润滑剂组元石墨和氮化硼制备的２种陶瓷摩阻材料的摩擦磨损特性进行了试验研究．结果表明：在给定的试验条件下，添加石墨或氮化硼都可以改善材料摩擦性能的稳定性；分别在１００℃，２００℃，３００℃和４００℃下定温试验时，这２种摩阻材料都具有较高的摩擦因数和良好的耐磨性，其中含氮化硼之摩阻材料的耐磨性比含石墨之摩阻材料的更好，前者在４００℃时的磨损率仅为后者在同温时的１／２．     

A NEW METHOD TO DETERMINE THE R-CURVE OF CERAMICS-FRACTURE GRATING METHOD

The etching technique of the single-lined zero-thickness specimen grating is applied tothe surface of the SiC fiber toughening Si_3N_4 ceramic composite specimen.The position of the crackand the crack length during the process of crack extension when the load is applied and gradually in-creased can be determined by recording the output voltage value of the Wheatstone bridge in which theceramic specimen with the fracture grating on is located.The crack-growth-resistance(R-curve) of thismaterialis thus obtained.     

载荷对Al2O3增强Y-TZP陶瓷磨损特性的影响

采用往复式摩擦磨损试验机研究了10%(质量分数计)Al2O3增强四方氧化锆多晶Y-TZP陶瓷材料(简称10ADZ)在不同载荷下的磨损行为与机制.结果表明:随着载荷的增加和滑动时间的延长,10ADZ陶瓷的磨损率增大,但并非呈线性增加,磨损率增长幅度不同;在62 N低载荷条件下,10ADZ陶瓷的磨损机制以犁沟和塑性变形为主;在124 N载荷下其主要的磨损形式为塑性变形、微切削和微断裂;而在310 N的高载荷下其主要的磨损机制为断裂磨损.     

陶瓷人工关节的跑合和摩擦性能研究

研究３种生物陶瓷材料（氧化铝，氮化硅和碳化硅）在水中的跑合及其摩擦特性。结果表明：跑合前，氮化硅－氮化硅摩擦副的起始摩擦因数和稳态摩擦因数最高，碳化硅－碳化硅磨擦副的起始摩擦因数和稳态摩擦因数最低，跑合后，氧化铝－氧化铝摩擦副的稳态摩擦因数最高，碳化硅－碳化硅摩擦副的起始摩擦因数和稳态摩擦因数仍然最低。当摩擦副表面均加工到超光洁状态（表面粗糙度Ｒａ为纳米数量级）时，碳化硅－碳化硅摩擦副的摩擦性能最