In traditional electrical discharge machining (EDM) of particle-reinforced metal matrix composites (PRMMCs), reinforcing particles tend to accumulate at the bottom of the discharge crater. This leads to a deterioration of the processing environment, resulting in undesirable discharge conditions such as arcing, which seriously affects the surface quality of the discharge crater and may even make processing difficult. To overcome this limitation, this study employs a step-pulse, increasing the instantaneous removal force to remove unmelted reinforcing particles wrapped in molten metal in the interpolar. This improves the discharge environment in the interpolar and increases processing efficiency, thus proposing an ejecting-explosion EDM (EE-EDM) method. Using SiCp/Al composites as the model material, together with a high-volume-fraction simulation model that explicitly embeds irregular particle geometries and random spatial distributions, thereby reproducing the microstructural geometry and spatial statistics of the PRMMCs. Combined with a high and low composite step-pulse waveform, a step-pulse vapor-jet driving source model is formulated. The study systematically investigates the material erosion and removal behaviors of PRMMCs during EE-EDM. Under equal input energy, EE-EDM delivers a 42.6% increase in MRR relative to EDM, confirming the efficiency of the EE-EDM removal mechanism. Agreement between simulation and experiment is evidenced by maximum dimensional deviations of 9.6% (radius) and 12.1% (depth) for discharge craters, validating the numerical framework. These outcomes establish a coherent theoretical framework for the EDM material removal mechanism of PRMMCs and provide actionable guidance for improving machining efficiency and surface quality.

SiCp/Al composites have excellent physical properties and are widely used in aerospace and other fields. Because of their poor machinability, they are often machined by non-traditional machining methods such as electrical discharge machining (EDM). In the process of EDM, due to the "shielding" effect of the reinforced particles of SiC, the local ejection force is low during the processing process, and it is difficult to throw the reinforced particles smoothly, which ultimately leads to a low material removal rate and poor surface quality. In this paper, a high-low-voltage composite ejecting-explosion EDM power supply is developed to explore the explosive effect of reinforced particles in the ejecting-explosion EDM process and the unique process law of the explosion process. The experiment platform uses self-developed CNC machining machine tools based on an ejecting-explosive EDM power supply, and the influence of a detonation-increasing wave on the processing of SiCp/Al composites with different volume fractions was studied by changing four factors: the open-circuit voltage difference, pulse current difference, pulse phase difference, and pulse width difference of the back wave behind the step front. The material removal rate and surface roughness were measured. The research results showed that the material removal rate could be increased to 164.63%, and the material surface roughness could be increased to 30.03% by adjusting the high and low pulse current difference from 1 A to 8 A. When the voltage difference between high and low wave (HLW) pulses increases from 40 V to 120 V, the material removal rate can be increased to 150.39%, and the material surface roughness can be increased to 20.49%. The material removal rate increases with the increase in pulse phase difference and open-circuit voltage difference. With the increase in peak current difference and pulse width difference, the material removal rate becomes faster at first and then slower. The surface roughness of materials increases with the growth of open-circuit voltage difference, peak current difference, pulse width difference, and pulse phase difference.

硬质合金是一种超硬材料,被广泛应用于机械制造尤其是航空航天、生物医疗仪器、模具制造等领域,由于极高的强度和硬度,对其材料表面进行机械磨削时会对磨削砂轮造成损害且磨削过程中产生大量的热量会导致工件的磨削烧伤及金相组织变化,影响硬质合金的使用性能。而电火花加工技术是靠工具和工件两电极间的脉冲性火花放电去除工件材料的,虽然不受材料强度和硬度等的限制,但其加工效率低且加工后的表面质量较差,不利于硬质合金材料的高效高质量加工。为此提出了超声辅助电火花磨削加工方法,即在电火花加工的基础上引入超声振动和电极旋转运动,强化放电区域工作介质的循环,提高加工效率并改善工件的表面质量。因此研制超声电火花磨削加工装置意义重大。研究内容如下:（1）对超声电火花磨削加工装置进行总体方案设计,包括电控系统和装置结构的方案设计。根据装置结构的设计方案,对装置的传动系统、动力系统等涉及的主要零部件进行选型与校核计算,对超声变幅杆支架及装置整体结构进行设计,绘制装置的三维模型图并进行装配关系的介绍,完成装置的研制工作。（2）研制了一套电火花加工电控系统,该电控系统包括脉冲电源及间隙控制系统两部分。基于脉冲电源的设计要求,采用可控式RC脉冲电源设计了粗、半精、精三种加工状态,并对三种加工状态进行性能测试。基于间隙控制系统的设计要求,采用全硬件电路的设计方法实时、快速的对间隙状态进行检测,并由单片机进行控制,根据间隙状态的检测结果驱使步进电机进给与回退,实现对间隙状态的自动控制。（3）使用研制的超声电火花磨削加工装置对硬质合金材料进行加工试验。探究不同电极材料对电极损耗的影响,以寻求一种高效低损的电极材料进行长时间的磨削加工试验。同时研究电流和电极转速的变化对硬质合金工件表面粗糙度及材料去除率的影响规律,结果表明:随着电流的增大,材料去除率增大,且表面粗糙度值也增大;随着电极转速的增大,材料去除率增大,但表面粗糙度值减小。并通过不同加工工况下的对比试验验证了超声电火花磨削加工可显著提升加工效率并改善工件的表面质量。本文所研制的超声电火花磨削加工装置具有体积小、成本低、加工效率高、脉冲能量可调、加工稳定性好等特点,可为后续研究硬质合金材料的表面去除加工提供试验装置的支持。

To study the change of residual stress during heating and solidification of SiCp/Al com-posites, a one-way FSI (Fluid Structure Interaction) model for the solidification process of the molten material is presented. The model used process parameters to obtain the temperature distribution, liquid and solid-state material transformation, and residual stress. The crack initiated by the thermal stress in the recast layer was investigated, and a mathematical model of crack tip stress was proposed. The results showed a wide range of residual stresses from 44 MPa to 404 MPa. The model is validated using experimental data with three points on the surface layer. © 2022 by the authors. Licensee MDPI, Basel, Switzerland.

钛合金由于表面硬度低及耐磨性差而发展受限，利用电火花沉积技术对其表面进行改性处理可提升钛合金材料工作性能。以NiCr–3为电极在钛合金表面制备了强化涂层，分析了工艺参数对涂层表面粗糙度、表面形貌及厚度的影响规律，分析了不同工艺条件下涂层的微观组织结构变化规律。结果表明，随着比沉积时间的增加，涂层厚度先增加后减小，最佳比沉积时间为4min/cm~2；随着沉积频率的增加，表面裂纹数量有所减少；随着沉积电压、沉积频率以及比沉积时间的增加，涂层硬度不断增大，最后逐渐趋于稳定。所获涂层是由基体中Ti元素与NiCr–3电极发生反应生成的反应涂层，涂层的主要成分是Ni3Ti、Ni2Ti、Cr2Ti和Cr1.93Ti1.07等相。

电火花沉积材料的过渡形式、过渡形态、结合过程等对沉积的效率、稳定性及沉积层质量有重要影响。为了探究电火花沉积的熔滴转移过程,建立了电火花沉积两极间熔滴过渡的仿真模型,模拟了电极表面熔融液滴变形及脱落的过渡过程,分析了过

To study the change of residual stress during heating and solidification of SiCp/Al composites, a one-way FSI (Fluid Structure Interaction) model for the solidification process of the molten material is presented. The model used process parameters to obtain the temperature distribution, liquid and solid-state material transformation, and residual stress. The crack initiated by the thermal stress in the recast layer was investigated, and a mathematical model of crack tip stress was proposed. The results showed a wide range of residual stresses from 44 MPa to 404 MPa. The model is validated using experimental data with three points on the surface layer.

针对SiC_(p)/Al复合材料电火花加工设计了工艺试验,并从复合材料的蚀除特性角度分析了峰值电流、开路电压、脉冲宽度对加工速度和表面粗糙度的影响,最后利用多目标遗传算法获得了加工电参数的最佳组合。结果表明:峰值电流、开路电压对

SiCp/Al复合材料因同时具有铝基体和碳化硅颗粒的综合特性,因此在具有低密度,高导热率的同时还具备了高硬度等优良特性,在各领域中备受青睐。然而具有高硬度的脆性SiCp/Al复合材料,使得传统的接触加工方式因切削温度过高,刀具磨损严重

电火花加工材料抛出过程十分复杂,其剧烈性、瞬时性和随机性导致了对这一过程的理解仍不甚清晰,制约了电火花加工加工效率的进一步提高。对电火花加工材料抛出过程涉及到的重要抛出力——热爆炸力的作用过程进行研究,对热爆炸力数学模