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针对煤矿液压支架油缸活塞杆（材质40Cr钢）服役过程中存在耐磨性、耐蚀性较低的问题,提出表面渗硼改性工艺。从活塞杆切取试样,利用金相、XRD、显微硬度、耐蚀性能测试等方法研究了试样在未调质和调质两种初始状态下经渗硼及渗硼后淬火对其渗硼层组织和性能的影响。研究结果表明：活塞杆渗硼前的调质可以促进硼化物的形成与析出,使其析出强化作用更显著;渗硼后再经淬火的渗硼层硬度略有降低,从表面到心部的硬度梯度有所减小,表面脆性降低,塑性和韧性提高。 相似文献
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The discoloration of Scot pine （Pinus sylvestris var. Mongolica） veneers caused by resin-eliminated treatment and the reversion of the color were studied. The result showed that the color of the veneers changed from buff to yellowish brown after the treatment of resin elimination and the discoloration of heartwood was more severe than that of sapwood; the degree of discoloration was significantly positively correlated with the medicament strength, temperature and resin-eliminated duration. The variance analysis showed the effects of those three factors on the discoloration were significant. With hydrogen peroxide （H2O2） as color reversion medicament and inorganic compound as medium of the reaction, the reversion of the color of heartwood was more inaccessible than that of sapwood; the degree of the color＇s reversion was positively correlated with the H2O2 strength, temperature and treating time; the H2O2 concentration has significant effects on the discoloration. In order to reduce discoloration of Scot pine veneers, medicament of resin-eliminated used have to be at some low concentration, and the optimal concentration of H2O2 is 0.35% during the process of color＇s reversion. 相似文献
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MPI提供了并行计算的一种消息传递接口。本文简述了MPI的关键技术,介绍了MPI的编程要点和思路,然后以经典问题LifeGame为例讨论了MPI程序的具体实现,最后给出了该程序的性能分析。 相似文献
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例1.故障现象:一台莺歌C47—4型彩电,无光栅无伴音。分析检修:检测电源各输出端电压均正常,测行输出变压器输出各级电压为零。检查行推动级电路,发现行推动管Q501集电极无电压。最后查出电阻R513(3.3kΩ/2W)引脚开焊。焊好R513后彩电有图像和伴音,但图像上部出现多条回扫线。用电容并接法查出自举升压电容C407(4.7μF/50V)无容量。更换C407后彩电工作恢复正常。2.故障现象:一台星海54CJ4Y型彩电,图像正常,但伴音时有时无。分析检修:敲击彩电机壳时伴音时有时无,说明机内有元件接触不良。检查时发现无伴音状态调音量键屏幕无音量符号显… 相似文献
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齿轮传动作为机械传动中主要的传动,设计方法已相当规范和标准,但设计过程相当复杂,通过对齿轮在工程设计中的地位和作用的分析,提出了一种以AutoCAD为支撑平台的齿轮设计与绘图一体化的总方案,从而建立了齿轮CAD系统 相似文献