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排序方式: 共有886条查询结果,搜索用时 15 毫秒
1.
为分析喷流冷却复合陶瓷薄片激光器的热特性,设计用于冷却复合陶瓷薄片的喷流冷却系统.利用湍流换热理论和计算流体动力学仿真方法建立喷流冷却复合陶瓷薄片激光器的流固耦合热仿真模型,定义评价其冷却能力和冷却均匀性的定量参数.根据该仿真模型得到喷流冷却系统的最优设计参数,并进行实验验证.使用163孔喷板,流量为0.2kg/s,入口温度为20℃,在1200 W泵浦时获得359 W激光输出功率,并测得复合陶瓷薄片上表面的最高温度为92℃.激光输出功率与复合陶瓷薄片上表面温度均与泵浦功率呈近似正线性关系,且温度的实验值与仿真值相符度较高. 相似文献
2.
Jutapol Jumpatam Bundit Putasaeng Narong Chanlek Prasit Thongbai 《Molecules (Basel, Switzerland)》2021,26(7)
The microstructure, dielectric response, and nonlinear current-voltage properties of Sr2+-doped CaCu3Ti4O12/CaTiO3 (CCTO/CTO) ceramic composites, which were prepared by a solid-state reaction method using a single step from the starting nominal composition of CCTO/CTO/xSrO, were investigated. The CCTO and CTO phases were detected in the X-ray diffraction patterns. The lattice parameter increased with increasing Sr2+ doping concentration. The phase compositions of CCTO and CTO were confirmed by energy-dispersive X-ray spectroscopy with elemental mapping in the sintered ceramics. It can be confirmed that most of the Sr2+ ions substituted into the CTO phase, while some minor portion substituted into the CCTO phase. Furthermore, small segregation of Cu-rich was observed along the grain boundaries. The dielectric permittivity of the CCTO/CTO composite slightly decreased by doping with Sr2+, while the loss tangent was greatly reduced. Furthermore, the dielectric properties in a high-temperature range of the Sr2+-doped CCTO/CTO ceramic composites can be improved. Interestingly, the nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were significantly enhanced. The improved dielectric and nonlinear electrical properties of the Sr2+-doped CCTO/CTO ceramic composites were explained by the enhancement of the electrical properties of the internal interfaces. 相似文献
3.
TiB2增强Al2O3陶瓷刀具高速干切削摩擦磨损性能 总被引:6,自引:2,他引:6
采用TiB2增强Al2O3陶瓷刀具对淬硬钢进行高速干切削试验,利用切削高温作用下的摩擦化学反应,在刀具表面原位生成具有润滑作用的反应膜,从而实现Al2O3/TiB2陶瓷刀具的自润滑.结果表明:低速干切削时,Al2O3/TiB2陶瓷刀具的磨损机制主要表现为粘着磨损和磨料磨损;而在高速干切削时,刀具的磨损机制主要表现为氧化磨损,刀具表面经由氧化反应生成具有润滑作用的反应膜而起到固体润滑作用,从而使刀具的耐磨性能提高,随着TiB2含量和切削速度的增加,反应膜的减摩抗磨作用增强;而在切削区通入氮气时,由于刀具表面氧化膜形成受阻,刀具的抗磨能力有所降低. 相似文献
4.
陶瓷刀具切削区温度场的计算机模拟 总被引:1,自引:0,他引:1
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 相似文献
5.
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。 相似文献
6.
采用程序升温热解吸(TPD/TDS)方法对Li4SiO4陶瓷小球的水解吸行为进行了实验研究。结果表明:水解吸过程中主要存在四个解吸峰;其中100℃附近的峰可解释为物理吸附水;150,250,400℃附近的峰可分别解释为以氢键、Li-OH和Si-OH配位键形式存在的化学吸附水。氚的释放与水的解吸几乎同步进行,且氚的释放形式主要为氚水(HTO),据此推测,氚水可能存在三种释放机制:(1)-OT+H2O→-OH+HTO;(2)-OH+-OH→H2O,-OT+H2O→-OH+HTO;(3)-OT+-OH→HTO。 相似文献
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9.
B.A. Goeckner D.R. Helmich T.A. McCarthy J.M. Arinez T.E. Peard J.E. Peters M.Q. Brewster R.O. Buckius 《Experimental Thermal and Fluid Science》1992,5(6):848-860
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. NOx 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. 相似文献
10.
D.A. Hall B. Cherdhirunkorn P.J. Withers T. Mori 《Journal of the mechanics and physics of solids》2005,53(2):249-260
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. 相似文献