混凝土氯离子渗透性试验方法综述

混凝土结构钢筋锈蚀主要是因氯离子由外部环境渗入混凝土中引起的。混凝土氯离子渗透性与暴露于氯化物环境的构筑物耐久性密切相关。文中简要介绍和评述混凝土氯离子渗透性的试验方法。     

天然气净化厂RBI与RCM 风险评价技术分析

结合川渝地区天然气净化厂开展RBI、RCM风险评价的实际情况,从评价对象、失效模式、评价方法、技术措施等方面对天然气净化厂开展的RBI、RCM风险评价技术进行了对比,分析了当前天然气净化厂开展RBI、RCM风险评价存在的问题,探讨了天然气净化厂RBI、RCM风险评价未来的发展趋势,希望藉此为天然气净化厂下一步RBI、RCM风险评价提供参考。     

基于RCM的数控机床维修管理研究

以数控机床为例,通过对RCM实施以及设备的可靠性分析的阐述,按RCM思想对设备的可靠性和故障后果,经过逻辑决断和有效性分析,确定设备的维修工作和工作周期,制订出相应的维修管理对策,说明RCM在设备维修中的应用.结果表明,RCM的应用有益于提高设备维修效率和准确度,其在设备维修管理中有良好的应用前景.     

Non-steady-state accelerated chloride penetration resistance of structural lightweight aggregate concrete

This study aims to characterise the chloride penetration resistance of structural lightweight aggregate concrete (LWAC) produced with different types, volumes and initial wetting conditions of lightweight aggregates (LWA), types of cement and contents of fly ash and silica fume, w/c ratios and curing conditions. A comprehensive experimental study was carried out involving three types of non-steady-state tests, which simulate different exposure conditions and penetration mechanisms. It is shown that the chloride penetration resistance is mainly affected by the cementitious paste and that high performance LWAC of 30–70 MPa can be produced. Regardless of the type of aggregate, we propose exponential relations to estimate the diffusion coefficient of chlorides. The volume and initial wetting condition of LWA had little influence on the chloride resistance. A long-term higher reduction of the diffusion coefficient was found in less dense LWAC. Reasonable correlations between the non-steady-state tests were obtained. Contrary to what is suggested in some European standards, the concrete strength cannot properly predict the durability behaviour of LWAC.     

Enhanced sintering and mechanical properties of 316L stainless steel with silicon additions as sintering aid

Abstract

Compaction, effect of ball milling, vaccum sintering, microstructures, volume shrinkage, interconnected porosity, thermal reactions and mechanical properties of 316L stainless steel with and without additions of elemental silicon have been investigated. It was found that the silicon addition enhanced the sintering process by providing a series of liquid phase reactions with the base powder which took place at temperatures below their melting points and the normal solidus range for stainless steels. Differential thermal analysis confirmed formation of liquid phases at three different temperatures which are believed to be responsible for the enhanced sintering process.The first two appeared at ~1060 and 1155°C by two exothermic peaks and the third one at ~1190°C by an endothermic peak. The ball milling operation provided higher green and sintered densities resulting in better mechanical properties due to less agglomorations with finer and much more uniform particle size distribution. Sintered densities of up to 7·44 g cm^-3 with tensile strength of 482 MPa, hardness value of 153 HV10 and 15% elongation were obtained with ball milled plus 3 wt-%Si addition. Low levels of interconnected porosities (~4%) were recorded within the temperature range 1250-1300°C suggesting the possibility of good corrosion resistance.

The sintered microstructures consisted of ferrite and austenite (duplex structure), complex silicide and eutectic phases within grains and at grain boundaries, pools of liquid (rich in Si) and some medium and small pores preventing full density to be achieved despite the liquid phase formation.     

澳大利亚/新西兰的RCM要求及EMC监管规定

澳大利亚和新西兰的符合性标签即将改革,详细介绍电气和电子设备、车辆和具有内燃机的设备的RCM要求,澳新的电磁兼容监管规定和设备的电磁兼容符合性规定,以及澳新的RCM符合性标签,包括其符号标识、供应商识别方法和申请方法。     

基于RCM5700的分布式仪表设计

为了满足飞行模拟器的需要,利用RCM5700能够支持快速以太网技术开发、具备较强性能的特点．结合步进电机控制设计了模拟器所需要的仿真仪表;优化了系统编程;数据传输部分充分利用了以太网带宽大,可扩展性强,结构简单,成本低廉的特点。通过实践检验,该仪表设计具有指示精度高、实时性好、速度快等优点。文章详细介绍了仪表的组成、工...     

高温后混凝土抗氯离子渗透性能的试验研究

用RCM法和电通量法2种方法测试了高温后不同配比混凝土的抗氯离子渗透特性,比较了2种方法的测试结果,并通过SEM观测了高温前后混凝土微观结构的变化.结果表明：高温前和高温后,混凝土强度等级对氯离子渗透性均有明显影响;随着温度升高,混凝土的氯离子渗透性不断提高,特别是当温度达到800℃时有显著增加;RCM法和电通量法所测指标的变化趋势基本一致,但RCM法能更为准确地反映出高温对各配比混凝土孔隙结构的影响规律;高温前后混凝土微观结构变化与其宏观上氯离子渗透性的变化规律相符.     

基于机械设备可靠性维护的管理系统的研究

以可靠性为中心的维护（RCM）分析理论引入设备维修保养体系,针对设备制定科学和有效的维护策略是提高其可靠性和安全性的必要手段。以可靠性为中心的维修不仅可根据设备的故障模式确定针对性的维修策略,而且充分考虑了设备的性能、维修经济性和维修策略之间的关系。文中基于对某公司可靠性的维修管理研究,结合对可靠性维修管理的深刻理解和认识,利用快速RCM分析提升公司的维修管理水平,具有一定的现实借鉴意义。     

Computer-aided RCM-based plant maintenance management system

In most of the industries, classical reliability-centered maintenance (RCM) is employed to decide the maintenance strategies using reliability data without having adequate interaction with the design and operational systems. This means that the RCM process will be conducted with no or limited access to the design and operational data/knowledge. Commonly, the developed maintenance strategies are implemented and managed within the computerized maintenance management system (CMMS), which is usually separate from the RCM automated environment. This paper presents the detailed system design and mechanism of improved RCM process as integrated with CMMS. The proposed solution is integrated with design and operational systems and consolidates some successful maintainability approaches to formulate an effective solution for optimized plant maintenance. The major components of the enhanced RCM process are identified and a prototype system is implemented as integrated with the various modules of the adopted CMMS (MAXIMO™). A case study is used to show the effectiveness of the proposed RCM-based CMMS solution in optimizing plant maintenance over the traditional approaches.