可磨耗封严涂层研究进展

可磨耗封严涂层是一种重要的热喷涂涂层,广泛应用于飞机发动机,对提高发动机效率、降低油耗进而提升发动机整体性能具有重要意义.本文介绍了可磨耗封严涂层材料的主要种类及其发展趋势,阐述了可磨耗封严涂层性能评价方法.     

新型苯基聚硅乙炔树脂的制备及其热性能

介绍一种新型的苯基聚硅乙炔树脂的制备方法及其热性能研究。采用1H-NMR和29Si-NMR对其结构进行表征。通过DSC、TGA、马弗炉、SEM等对其热稳定性及高温抗氧化性进行了初步表征。TGA测试结果表明树脂固化物在1000℃氮气中残重率为86%,在空气中残重率为54%,马弗炉800℃高温处理30min残重率为79%。该树脂具有优良的高温热稳定性及高温抗氧化性,有望用于耐高温基体树脂。     

高热导率聚酰亚胺浸渍漆

文摘通过引入无机纳米粉体研制了高热导率聚酰亚胺浸渍漆,研究了聚酰亚胺的化学结构、无机粉体的种类、粒径和用量等因素对浸渍漆贮存稳定性以及固化物性能的影响。均苯四甲酸二酐与4,4′-二氨基二苯基醚合成的聚酰亚胺具有高的热导率。在联苯型聚酰亚胺中引入30%~35%、粒径为100~300 nm的α-A l2O3粉体,固化物的热导率可提高到0.65~0.80 W/(m.K),其余性能基本保持原有水平。     

Interior Evolution of Mercury

The interior evolution of Mercury—the innermost planet in the solar system, with its exceptional high density—is poorly known. Our current knowledge of Mercury is based on observations from Mariner 10’s three flybys. That knowledge includes the important discoveries of a weak, active magnetic field and a system of lobate scarps that suggests limited radial contraction of the planet during the last 4 billion years. We review existing models of Mercury’s interior evolution and further present new 2D and 3D convection models that consider both a strongly temperature-dependent viscosity and core cooling. These studies provide a framework for understanding the basic characteristics of the planet’s internal evolution as well as the role of the amount and distribution of radiogenic heat production, mantle viscosity, and sulfur content of the core have had on the history of Mercury’s interior. The existence of a dynamo-generated magnetic field suggests a growing inner core, as model calculations show that a thermally driven dynamo for Mercury is unlikely. Thermal evolution models suggest a range of possible upper limits for the sulfur content in the core. For large sulfur contents the model cores would be entirely fluid. The observation of limited planetary contraction (∼1–2 km)—if confirmed by future missions—may provide a lower limit for the core sulfur content. For smaller sulfur contents, the planetary contraction obtained after the end of the heavy bombardment due to inner core growth is larger than the observed value. Due to the present poor knowledge of various parameters, for example, the mantle rheology, the thermal conductivity of mantle and crust, and the amount and distribution of radiogenic heat production, it is not possible to constrain the core sulfur content nor the present state of the mantle. Therefore, it is difficult to robustly predict whether or not the mantle is conductive or in the convective regime. For instance, in the case of very inefficient planetary cooling—for example, as a consequence of a strong thermal insulation by a low conductivity crust and a stiff Newtonian mantle rheology—the predicted sulfur content can be as low as 1 wt% to match current estimates of planetary contraction, making deep mantle convection likely. Efficient cooling—for example, caused by the growth of a crust strongly in enriched in radiogenic elements—requires more than 6.5 wt% S. These latter models also predict a transition from a convective to a conductive mantle during the planet’s history. Data from future missions to Mercury will aid considerably our understanding of the evolution of its interior.     

准直光学系统热变形对太阳模拟器性能影响研究

为了给太阳模拟器系统热管理提供可靠的技术依据,研究了准直光学系统热变形对系统性能的影响。选取项目组自主研发的高精度太阳模拟器准直光学系统作为研究对象,利用有限元软件仿真实际工作条件下各光学元件表面温度及热变形分布,将通光表面变形数据拟合为泽尼克系数导入光学设计软件中,分析热变形对系统准直角误差及辐照均匀度影响。研究结果表明:在未采取温控措施的自然对流条件下,热变形造成±1’的准直角误差和41.3%的辐照不均匀度,超出允许范围,需进行温控。通过光机集成分析法,给出了不同温度下,对流系数与热变形导致的准直角误差和辐照不均匀度对应关系,为风冷温控系统工程化设计提供了依据。     

数字温度二次仪表检定装置的测量不确定度评定

介绍了数字温度二次仪表检定装置检定配热电偶和配热电阻用温度二次仪表的原理和方法,并分别探讨了配热电偶和配热电阻时测量结果不确定度的评定。     

提高低导热材料表面温度均匀性方法的研究

比较了不同低导热材料的高温热导率测试装置特点,确定了在整体加热方式下试样表面温度均匀性差是限制测试准确度提高的一个原因,提出采用分区加热的方法改善试样表面温度均匀性。选取三种不同热导率范围的材料作为被测试样,分别做了试样整体加热和分区加热的模拟计算。结果表明,整体加热方式只能在试样表面中心有限区域形成均温区,而分区加热方式能显著改善试样表面温度均匀性。     

卫星热控电压测量模块研制

卫星热控电压测量是保障卫星可靠性、安全性的重要环节。由于测量的特殊性,要求研制与整星热控系统相适合的电压测试模块。采用信号隔离、输入保护等措施保证测量的安全性;采用较高分辨力数据采集及量化技术、以及自校准技术保证测量的可靠性。通过微处理器控制测量过程,LAN接口实现计算机数据传输和通信控制,提高了测量效率。     

基于ARM9的宽频功率源接口电路设计

结合研制工作实际,介绍一种以ARM9为核心的宽频功率源接口电路设计方案和程序设计方法。给出了电路设计方案,介绍各电路模块的功能和设计思想。在介绍VxWorks操作系统架构的基础上,给出了应用程序设计的详细流程。     

化学热处理对40Cr钢表象疲劳极限影响的定量化研究

选用40Cr结构钢制备光滑试样和缺口试样(Kt=2.4),经调质并采用氮化进行表面强化。在旋转弯曲疲劳试验机和扭转疲劳试验机上测定氮化和未氮化试样在应力比R=-1条件下5×106循环周次的表象疲劳极限。试验结果表明,氮化后疲劳缺口敏感系数q趋近0,本文用疲劳裂纹萌生的微细观过程理论对此作了合理清晰解释。氮化使光滑试样的表象疲劳极限提高36%,使缺口试样的表象疲劳极限提高96%,并将疲劳裂纹源从表面"挤到"次表面层。在试验研究和理论分析的基础上,从疲劳性能方面提出了表面强化工艺的优化判定准则:若表面强化后疲劳裂纹源位于表面强化层下基体,或者其表象疲劳极限达到按"表面/内部疲劳极限概念"预测的数值,则此表面强化工艺已达到优化。