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几种火焰喷焊自熔性合金层的耐磨性能 总被引:7,自引:0,他引:7
研究了不同自熔性合金粉末火焰喷焊层的显微组织与抗磨粒磨损性能,并对其磨面形貌进行了SEM观察分析。结果表明,在Ni60自熔性合金中加入适量的镍包WC粉末可明显提高其喷焊层的抗磨粒磨损性能。当WC的加入量为35%(wt)左右时,该喷焊层与60Si2Mn调质钢相比,相对的耐磨性可提高6倍以上。 相似文献
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本文研究了加稀土与不加稀土的Fe-B-Si非晶粉末涂层经激光重熔后的组织与性能。结果发现,加入稀土元素的激光重熔合金化层硬度HV从未加稀土的685提高为1180;磨损体积由未加稀土时的0.86减少到0.42;其硬度、耐磨性均比未加稀土的提高一倍左右。显微组织分析表明,加入稀土的激光重熔合金化层有马氏体相变发生,其基体组织为奥氏体及部分马氏体枝晶、碳化物、合金化合物与奥氏体及马氏体共晶组成。未加稀土的激光重熔合金化层中没有马氏体相变发生,基体组织为奥氏体枝晶和枝晶间的枝杈状、锯齿状、碳化物、合金化合物等共晶组成。 相似文献
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气门密封面激光熔覆的工艺和性能研究较多,但激光熔覆的合金组织和性能与现在气门密封面生产应用的等离子喷焊合金的对比数据较少.为了推动激光熔覆技术在气门密封面生产中的应用,对目前应用的气门WF218合金进行了激光熔覆层与等离子喷焊层的对比研究.通过对同炉气体雾化生产的WF218合金粉末分别进行激光熔覆和等离子喷焊,对两者合金层研究结果显示,激光熔覆合金层更致密、组织更细小、成分更均匀、耐蚀性和耐磨性更好.根据研究数据,激光熔覆技术应用于气门密封面生产将进一步提高质量. 相似文献
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本文研究表明,稀土使喷焊层组织中亮白区和树枝状晶区减薄或消失;金属化合物(游离状)的分布与形态改变;既可提高也可降低喷焊层硬度,但是提高了耐磨性。 相似文献
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A method is proposed for estimating the parameters of a mixture of exponential and Weibull distributions for which the accuracy of preliminary estimates obtained by graphical analysis is refined in accordance with the criterion of maximum likelihood. The efficiency of the proposed method is supported by the results of statistical modeling. 相似文献
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An approximate analytical expression is derived for the velocity of the front of the wave of change of boiling modes on a
rod and on a plate. The impact of the Thomson effect and of the heater orientation in the gravity field is included. Adequate
agreement is demonstrated between the derived relations and experimental data. 相似文献
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Liebert A Wabnitz H Grosenick D Möller M Macdonald R Rinneberg H 《Applied optics》2003,42(28):5785-5792
A novel method for the determination of the optical properties of tissue from time-domain measurements is presented. The data analysis is based on the evaluation of the first moment and the second centralized moment, i.e., the mean time of flight and the variance of the measured distribution of times of flight (DTOF) of photons injected by short (picosecond) laser pulses. Analytical expressions are derived for calculation of absorption and of reduced scattering coefficients from these moments by application of diffusion theory for infinite and semi-infinite homogeneous media. The proposed method was tested on experimental data obtained with phantoms, and results for absorption and reduced scattering coefficients obtained by the proposed method are compared with those obtained by fitting of the same data with analytical solutions of the diffusion equation. Furthermore, the accuracy of the moment analysis was investigated for a range of integration limits of the DTOF. The moment analysis may serve as a comparatively fast method for evaluating optical properties with sufficient accuracy and can be used, e.g., for on-line monitoring of optical properties of biological tissue. 相似文献
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水三相点是开尔文热力学温度的唯一基准点,也是ITS-90国际温标重要的定义固定点。因此,水三相点不确定度分析对整个温标的建立、温度量值传递起着至关重要的作用。近3年来,中国计量科学研究院研制出一系列高质量的水三相点容器,加强了水三相点的研究,为不确定度的分析提供了更为可靠的实验依据。同时,不确定度的分析也是客观评价新研制容器性能的一个重要指标。因此,根据实验结果对新研制容器所复现的水三相点进行了不确定度评定。评定结果表明,其扩展不确定度为0.16mK(k=2.69,P=0.99)。 相似文献
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