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采用水雾化铁粉,分别加入不同含量的润滑剂,以常温压制与温压两种压制方式成形,温压温度为130℃;测量了压坯、烧结坯的密度和弹性后效,并进行了对比与分析.结果表明:润滑剂的适量加入可以提高粉末的流动性以及减小其与模壁间的摩擦力,从而得到更高的压坯密度与烧结密度,加入量最佳值为0.4%(质量分数)左右;同时,温压可提高粉末的生坯密度、烧结密度,并且可以降低弹性后效和脱模力;常温压制的压坯密度和烧结坯密度最高值分别为6.89和7.10 g·cm-3,而温压的则提高至7.06和7.26 g·cm-3. 相似文献
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从实际工作过程中润滑剂对滚动轴承寿命、摩擦力及运转温度的影响等方面阐述了润滑剂在轴承工作过程中所起到的重要作用。 相似文献
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为了在降低摩擦材料成本的同时,保证摩擦材料性能良好,在原有配方基础上尝试改变铁粉粒度和种类,即把80~300目的泡沫铁粉替换成粒度大小为20~120目的泡沫铁粉或325目的还原铁粉,采用相同的热压成型技术和热处理工艺制备摩擦材料试样。采用洛氏硬度计测试试样的硬度,采用定速式摩擦试验机测试试样的摩擦磨损性能,采用扫描电镜观察试样的磨损面形貌,研究其磨损机制。结果表明:当采用较大的泡沫铁粉粒度时,随着其含量的增加,平均摩擦因数和磨损率会提高,但摩擦因数稳定性提高;还原铁粉具有明显的增摩作用和热衰退现象,尤其在恢复过程,摩擦因数变化大且不稳定,但磨损率低。20~120目泡沫铁粉可提高材料的摩擦因数稳定性,且可相对减轻材料的磨粒磨损和疲劳磨损,因而可用于代替80~300目泡沫铁粉。 相似文献
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MoS 2 -Ti composite solid lubricant films were deposited on an AISI D2 tool steel and silicon wafer by CFUBMS (closed field unbalanced magnetron sputtering). The deposition process was performed for nine different test conditions at various levels of target current, working pressure, and substrate voltage using the Taguchi L 9 (3 4 ) experimental method. It was observed that the chemical composition of MoS 2 -Ti composite films was significantly affected by sputtering parameters. It was determined that the microstructure of composite films is neither crystalline nor amorphous; in other words, it is quasi-amorphous, and (002) and (100) planes characteristic of MoS 2 occurred. The friction coefficients of the films were determined over 1800 s and at a loading of 10 N by means of a pin-on-disk tribotester. The changes in friction coefficient were related to structural changes based on Ti addition and the different levels of deposition parameters. 相似文献
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Flow meters in thermal power plants are operated at high temperatures and pressures and often encounter disturbed flow profiles. This leads to an increased measurement uncertainty, limiting the safe operating range of flow rates and thus, the plant's power output. To respond to this shortcoming, the laser optical flow rate standard (LFS) was developed. The LFS is designed to allow the on-site calibration of industrial flow meters in power plants at high temperatures and pressures. It makes use of the laser Doppler anemometry (LDA), as a fundamental and non-invasive method, to measure the velocity field simultaneously with two LDA systems. The volumetric flow rate is then determined by means of integration. Here, we present flow rate measurements for a fully developed pipe flow and for six pipe diameters downstream of a disturbance generator. The mean deviation in flow rate between the two LDA systems was 0.05%, with a mean deviation from the gravimetric reference flow rate of 0.12%. The highest deviations from the reference were 0.21% and 0.31%, for the first and second system respectively. 相似文献
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本文介绍了材料燃烧性能试验中采用玻璃管转子流量计计算气体流量时,将流量计读数转换为工业标准状态下流量的换算方法。 相似文献
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光学薄膜的堆积密度通常是利用薄膜在真空及大气中折射率的变化来计算,在IAD实验中,我们发现有些薄膜的堆积密度大于1.0,这意味着薄膜的密度比自然界中的材料密度还要密积,原因是薄膜具有较大的内压应力,我们还发现了薄膜的波漂不依从于堆积密度。这是因为它们在不同的蒸发条件下具有不同的密度均匀性,在用EB及不同条件的IAD的情况下,我们计算并分析了堆积密度及密度均匀系数,并用SEM 观察了薄膜的微结构。 相似文献
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针对ISO6358标准及其流量扩展表示式在描述多孔质气动元件流量特性上的缺陷,考虑多孔介质内部气孔率和流体基本流动规律,基于Darcy-Forchheimer定律对多孔质气阻元件建立流量特性模型。空气在多孔质内流速较低时,利用Darcy定律表示流速与压力梯度的关系;当流速增大到一定程度时,通过在Darcy定律的基础上增加一个惯性项构成Forchheimer定律来表征流动特性。采用4种不同尺寸,不同气孔率的烧结金属多孔质气阻进行流量特性试验验证。将流量特性分段进行处理,对模型中的渗透系数和惯性系数提出相应的参数辨识方法,即通过对小压差区域的试验数据进行线性拟合来获取渗透系数,而利用雷诺数大于0.1的数据通过高斯——牛顿非线性最小二乘法确定惯性系数。试验结果表明,该模型可以准确表示被测元件的流量特性,计算结果相对试验误差小于2%。同时,试验系统能够保证渗透系数测试误差小于3%,测试精度足以满足绝大多数工业场合的要求。 相似文献