考虑热损失的热丝TIG焊热丝温度分布解析模型

基于能量守恒定律建立了考虑热损失的电阻加热热丝温度分布的数学解析模型,验证了此解析模型的计算结果与文献中的实测数据的基本吻合性,并讨论了焊丝直径、热丝电流、送丝速度以及焊丝伸出长度等因素对热丝温度分布的影响规律.结果表明,此数学解析模型具有很高的准确性,可以用来进行热丝加热过程的分析以及焊接质量的控制;焊丝直径越小、热丝电流越大、送丝速度越小,焊丝伸出部分上距给电点相同距离的温度越高;焊丝伸出长度越大,焊丝伸出部分距焊丝送入位置相同距离的温度越高.

EACVD金刚石膜热丝温度的单片机测控

在EACVD金刚石膜生长过程中,衬底温度、热丝温度、热丝电流和气源流量等是其重要的工艺参数。鉴于手动控制的不精确,采用了单片机M SP 430控制热丝温度,对其他工艺参数进行了监测。介绍了计算机测控系统硬件组成和软件实现。采用模糊P ID控制后,热丝温度控制精度为2℃,生长速率达到10μm/h以上。实验结果表明,所研制的测控系统运行可靠,使用方便,初步实现了金刚石厚膜稳定优质生长。

热丝CVD工艺参数对GeSi薄膜键结构影响的研究

对高H2稀释比条件下热丝CVD法制备GeSi薄膜的工艺参数对薄膜的键结构的影响进行了研究。用Raman谱和FT-IR谱对薄膜中非极性键(Ge—Ge、Ge—Si和Si—Si)相对含量的变化和极性键(Ge—H、Ge—H2、Si—H等H键)相对含量的变化进行了分析。研究结果表明,热丝CVD工艺参数对制备的GeSi薄膜中非极性键和极性键的影响规律是不同的。热丝温度和锗烷硅烷流量比(RS/G)对非极性键相对含量的变化均有影响。随着热丝温度上升Ge—Si和Si—Si相对含量均增加。随着RS/G增加Si—Si相对含量一直增加,Ge—Si相对含量先增加,当RS/G>1.4时开始下降。但热丝温度和RS/G对H键的影响规律有很大不同:随着RS/G增加,Si—H键的相对含量增加,Ge—H和Ge—H2键的相对含量减少,而热丝温度对H键相对含量基本无影响。

热丝化学气相沉积技术低温制备多晶硅薄膜的结构与光电特性

以金属W和Ta为热丝 ,采用热丝化学气相沉积 ,在 2 5 0℃玻璃衬底上沉积多晶硅薄膜 .研究了热丝温度、沉积气压、热丝与衬底间距等沉积参数对硅薄膜结构和光电特性的影响 ,在优化条件下获得晶态比Xc>90 % ,暗电导率σd=10 - 7— 10 - 6 Ω- 1 cm- 1 ,激活能Ea=0 5eV ,光能隙Eopt≤ 1 3eV的多晶硅薄膜 .

Improvement of Critical Heat Flux Performance by Wire Spacer

In order to investigate the coolability of a tight lattice core in BWR （boiling water reactors）, an experiment of CHF （critical heat flux） was conducted using a single heater pin flow channel with and without a wire spacer with the mass flux ranged from 200 kg/（m2.s） to 600 kg/（m2·s）, the inlet temperature from 50 ℃ to 90 ℃ at the pressure of 0.1 MPa. The results of CHF values were compared between two different types of heater pin with and without the wire spacer. The heat removability of flow channel was improved by the wire spacer in comparison with the heater pin flow channel without the wire spacer. The CHF value was higher in the heater pin channel with the wire spacer than in that without the wire spacer.

Thermodynamic evidence for cluster ordering in Cu_(46)Zr_(42)Al_7Y_5 ribbons during glass transition

This work investigated the response of Cu46Zr42Al7Y5 glass ribbons to both dynamic and static heating using differential scanning calorimeter （DSC）. The DSC curve manifests three exothermic responses to dynamic heating, among which the first and the third one are the signatures of the normal sub-Tg （Tg, glass transition temperature） relaxation and the crystallization process, respectively. The second one is attributed to a partial overlap between the endothermic response to the glass transition and the exothermic response to the formation of ordered clusters. The cluster ordering, which begins at the final stage of glass transition, has been verified by the differences in the activation energy of the sub-Tg relax- ation, the cluster ordering and primary crystallization for both the as-spun and annealed ribbons. The cluster ordering could be driven by the large difference between the Zr-Y mixing enthalpy and the Al-Y （or Cu-Y） mixing enthalpy. The findings contribute to distinguishing between phase separation and clusters motion scenarios.