应用压痕断裂力学分析陶瓷材料的磨削加工

应用压痕断裂力学分析陶瓷材料的磨削加工过程,根据陶瓷材料的脆性指数确定临界磨削力,分别建立了磨削主应力极值与泊松比和磨削分力比之间的回归方程,此简单函数便于计算最大磨削主应力和分析磨削裂纹.脆性指数和泊松比反映陶瓷材料的磨削加工性,磨削方式影响陶瓷材料的去除,通过陶瓷磨削实验证明分析结果.研究结果为陶瓷材料磨削参数的选择和磨削方式的确定提供了理论依据.     

可加工陶瓷材料机械加工技术的研究进展

随着可加工陶瓷材料的研发与应用,可加工陶瓷材料的机械加工技术逐渐成为当今的研究热点之一.本文综述了可加工陶瓷在机械加工过程中的材料去除特性、刀具磨损、加工工艺及可加工性评价,内容涉及加工表面质量、去除机理、加工损伤、材料去除率、刀具参数、切削参数、表面粗糙度、冷却和可加工性综合评价,并提出了今后的研究发展方向和趋势.     

可加工陶瓷材料的机械加工技术

介绍云母玻璃陶瓷、氧化物陶瓷和非氧化物陶瓷3类可加工陶瓷材料的显微结构特性与材料可加工性的关系，层片状结构与弱界面使陶瓷材料具备可加工性。分析了可加工陶瓷材料机械加工过程中的特性；适宜的加工工艺参数、低加工损伤及材料的沿晶界断裂模式。结合金属材料的可加工性研究，讨论了适于陶瓷材料可加工性评价的研究方法。     

陶瓷材料延性域磨削机理

从陶瓷磨削加工过程,磨料加工时有效材料去除率,加工的临界磨削深度与材料本身的性质以及材料的破坏形式等角度分析了陶瓷材料延性域磨削加工的可行性.介绍了一些典型的以压痕断裂力学理论为基础建立的陶瓷材料延性域磨削加工的数学模型,从理论上探讨了陶瓷材料延性域超声磨削机理.给出了延性域超声磨削的临界条件,并利用自主研制的五轴联动数控超声磨削机床在ZrO2陶瓷上加工出叶片型面.对陶瓷材料延性域超声磨削加工技术的发展作了展望.     

可加工陶瓷结构设计及研究进展

从微观结构设计出发,进行可加工陶瓷制备与性能的研究已成为陶瓷材料研究领域的热点之一。本文对各类可加工陶瓷的结构设计及其研究进展作一综合评述,并对结构陶瓷可加工性与材料结构设计的关系以及陶瓷材料可加工性的评估及表征进行了简要介绍。     

石英陶瓷比磨削能正交试验研究

磨削是陶瓷材料最常用的加工方法,选择合理的工艺参数,降低加工成本是陶瓷磨削加工研究的重要内容.通过大量的正交试验,研究陶瓷材料在低速下的磨削性能,优化陶瓷磨削参数,对于丰富陶瓷磨削理论,指导实际生产具有重要的现实意义.     

工程陶瓷材料磨削加工技术研究

工程陶瓷材料具有优良的物理、化学、力学性能,在许多领域得到广泛的应用。目前,使用金刚石工具(主要是砂轮)的磨削加工是工程陶瓷去除加工的基本途径。本文概述了陶瓷材料磨削加工技术的进展,并对磨削后的陶瓷工件表面损伤进行了分析。     

采场结构参数的层次分析和模糊数学综合评价

针对影响采场结构参数选择的复杂因素,提出了一种基于层次分析法和模糊数学的综合评价方法.在评判优选过程中,综合考虑各动态、静态、定量、非定量指标,如经济、安全、技术等指标,运用层次分析法确定各因素权重,根据模糊数学原理选择合理的隶属度函数,建立模糊综合评判模型,进行模糊优选.以康家湾矿拟采用的分段空场嗣后充填法为例,根据数值模拟结果从9种待选结构参数组合中筛选6种方案,进行模糊综合评判,得出各方案优越度分别为96.3%、77.1%、96.6%、82.2%、89.1%、79.0%,最终确定方案5最优,其矿房跨度20 m,间柱4 m,顶板厚度4 m.     

石油加工方案的综合评价与优选模型

石油加工方案的优劣受众多指标的影响,这些指标的性质、量纲、单位、方向往往不统一,这就决定了石油加工方案优选不能以直接比较各指标值或某一指标的大小来决定方案的优劣.合理的方案优选必需综合考虑各指标信息、各指标特性,进行综合评判,从而得出方案的优劣.本文分析了石油加工方案的综合评价指标体系,采用定性和定量分析相结合、主观和客观分析相结合的方法建立了多目标综合评价与优选模型,其中包括定性指标的量化、基于主观分析(层次分析法)和客观分析方法(熵权法)相结合的权重的确定、距离综合评价方法的应用.本文以某炼化一体化炼厂原油加工方案的评价与优选为例,建立了该厂综合评价指标体系,利用该模型进行计算,得到了合理的评价结果.     

复合合金化对奥氏体中锰钢切削加工性的影响及切削加工性的模糊综合评判

在传统奥氏体中锰钢中添加不同含量的合金元素Mo, Cr, Nb和RE进行复合合金化处理,测试了其导热性及切削加工性,研究了复合合金化对奥氏体中锰钢切削加工性的影响,建立了二级模糊综合评判模型,以奥氏体锰钢的硬度、抗拉强度、延伸率、冲击韧性和热导率作为影响因素,对切削加工性进行定量分析. 结果表明,复合合金化处理可一定程度上改善奥氏体锰钢的切削加工性,合金元素Mo, Cr和Nb含量分别为1.87wt%, 2.43wt%和0.059wt%时试样的刀具后刀面平均磨损宽度VB值比未经合金化处理的ZGMn13钢减少了14.3%. 用二级模糊综合评判模型对奥氏体锰钢的切削加工性进行评价,通过本模型获得的评价指标与刀具磨损实验获得的VB值相关性显著,相关系数为–0.87334,存在高度的线性负相关,评判结果与VB值基本一致,评判模型符合生产实际,结果准确有效.     

Study on the effect of ultrasonic vibration-assisted polishing on the surface properties of alumina ceramic

Due to the excellent biocompatibility and chemical durability, alumina ceramics are widely used in biomedical fields such as dentistry. Meanwhile, the high hardness and brittleness of the alumina ceramic causes difficulties in ensuring the processing quality of conventional machining methods. Ultrasonic vibration-assisted polishing (UVAP) can effectively improve the surface quality of hard and brittle materials as a novel machining method. The surface properties of the alumina ceramic for different ultrasonic amplitudes are obtained in this study. The evaluation of the surface properties includes microscopic topography, frictional property, surface hardness, microscopic strain, and surface roughness. In addition, a surface roughness model of the alumina ceramic is built based on the UVAP machining mechanism. The model considers the effect of different types of abrasive particles (free and fixed abrasive particles) on the material removal mechanism. The experimental results show that the errors of the predicted model are less than 20%. This work will provide some ideas for the subsequent UVAP processing.     

A comprehensive review of electric discharge machining of advanced ceramics

Advanced ceramics are widely used in high temperature and wear related situations due to their unique physical and chemical characteristics. With the increasing demand for ceramics, the machining techniques of ceramics become a hot and tough issue because ceramics are extremely fragile and difficult to process. Traditional mechanical machining techniques like milling, turning, and drilling are subjected to large cutting forces and heat leading to extensive tool wear and poor machining performance. Electric discharge machining (EDM) has an outstanding ability of no-contact machining brittle and hardness materials with complex shapes via generating extreme high-temperature plasma channel to melt and vaporize materials. Therefore, in this paper, the research trends of latest EDM technologies for advanced ceramic materials were comprehensively reviewed. Firstly, according to the electrical conductivity of advanced ceramics, different EDM processes were introduced in details. Secondly, the existing physical models and material removal mechanisms of EDM process of ceramics were compared and analyzed. Then the machining performance indicators, such as MRR, Ra, TWR, surface topography, and micro-structures, were respectively investigated. Additionally, the new hybrid machining techniques of EDM were presented to provide some potential for efficiently machining advanced ceramics. Eventually, this paper also discussed the challenges associated with electrical discharge machining of advanced ceramic materials, and suggested some related research areas which possibly attract significant research attentions in the future.     

Laser surface texturing of ceramics and ceramic composite materials – A review

The surface texturing of ceramics is generally performed through acid-based etching and machining; however, laser texturing may be considered as a more precise, reproducible and eco-friendly process. Furthermore, laser ablation may be used to produce complex patterns on ceramic surfaces, thus offering new surface engineering opportunities. The studies so far conducted on this topic have mainly been application-driven, and since a wide variety of lasers have been used for surface texturing, it is difficult to have a comprehensive understanding of this technique applied to ceramics and ceramic composite materials. Laser texturing requires a great deal of knowledge of the material and the laser source parameters to optimise the process in order to obtain the expected results. It is therefore important to expand the research on the laser texturing of ceramics and CMCs in order to build a relevant amount of literature that can be used to identify the most appropriate parameters for each application. This review provides an overview of most of the technological aspects considered relevant for the laser surface texturing of ceramics and CMCs, and includes the fundamentals of laser-material interactions and a summary of the used equipment and parameters. Furthermore, most of the techniques related to the modifications of surface material induced by a laser are critically reviewed, and the new horizons that are opening up, in the context of the modification of surfaces to improve the performances of materials for several applications, are discussed.     

ZrO2/CePO4可加工陶瓷材料钻削加工的试验研究

分别用高速钢刀具和硬质合金刀具对ZrO2/CePO4可加工陶瓷材料进行钻削加工试验.通过比较ZrO2/CePO4陶瓷和低碳钢材料的加工过程,分析了ZrO2/CePO4陶瓷的加工特性、材料钻削规律及其影响因素.实验结果表明:刀具的磨损是ZrO2/CePO4钻削加工的主要特征之一.钻削ZrO2/CePO4陶瓷材料的去除过程可分为高效率和高磨损2个阶段,刀具材料影响ZrO2/CepO4可加工陶瓷材料的加工效率.可加工陶瓷的加工过程中,应选择合理的刀具参数和加工工艺参数,以获得良好的加工质量.     

陶瓷零件的加工方法

工程陶瓷具有极高的硬度、良好的耐磨性和耐腐蚀性以及脆性大等特点，属于难加工材料，特别是加工高精度、形状复杂的构件非常困难。陶瓷材料作为工程材料的大规模推广应用，在很大程度上取决于陶瓷零件加工技术的发展。笔者综述了陶瓷零件的加工方法及最新进展。     

Damage formation and suppression in rotary ultrasonic machining of hard and brittle materials: A critical review

Rotary ultrasonic machining (RUM) combines diamond grinding with small-amplitude tool vibration, to improve machining processes of hard and brittle materials. It has been successfully applied to the machining of a number of brittle materials from optical glasses to advanced ceramics as well as ceramic matrix composites. The emphasis of this literature review was on formation mechanism and suppression methods of machining induced damages that truly limit RUM machining efficiency improvement of brittle materials. In this review paper, material removal mechanism and cutting force modeling of RUM of brittle materials were presented, as well as all corresponding roles in the damage formation process. The critical processing capacity of RUM machine tools was described, which guarantees the RUM effectiveness and consequently constitutes the boundary condition of processing parameters determination. Formation mechanisms of edge chipping, tearing defects, subsurface damages, and their interactive effects were summarized. Advances in damage suppression methods were also described, including optimization of processing parameters, tool design of low damage, and other methods such as rotary ultrasonic elliptical machining.     

可加工陶瓷材料研究进展

介绍了国内外可加工陶瓷材料的研究现状,包括可加工玻璃陶瓷、可加工Ti_3SiC_2陶瓷、可加工SiC、Si_3N_4陶瓷、可加工复相陶瓷以及可加工陶瓷的各种加工技术,并对其发展趋势进行了展望。     

Determination of the grindability of coals, shales and other minerals by a modified Hardgrove-machine method

The Hardgrove-machine method for determining the grindability of coal may be applied to shales and other minerals provided a 75 cm³ grindability sample is used instead of the 50 g size to which, for coal, it is equivalent. A measuring cylinder and a procedure for taking a sample of constant volume are described. Grindability tests on samples of different quantities showed that the amount of −200 mesh material produced was reasonably constant for the 75 cm³ sample volume irrespective of the density of the material. Grindability results may be expressed in terms of either the volume or the weight of −200 mesh product depending on the information required, and appropriate indices of grinding softness or hardness are suggested. The results of a large number of grindability tests on coal, carbonaceous shales, and shales have been statistically analysed to determine the magnitude of errors in sample preparation, in loss of product material, and in the overall determination.