电弧喷涂4Cr13涂层的组织与性能研究

研究了喷砂粗化、喷涂打底涂层、电拉毛三种表面预处理工艺下电弧喷涂4Cr13涂层的组织与性能.利用扫描电镜、能谱仪等手段对涂层组织和断口形貌进行分析,同时对涂层的显微硬度和结合强度进行了测试.结果表明:电弧喷涂4Cr13涂层组织呈现出典型的层状结构.不同的表面预处理工艺对涂层的结合强度影响显著,喷砂粗化并喷涂打底涂层能使...     

电弧喷涂4Cr13涂层预处理工艺及组织与性能研究

采用喷砂粗化、喷砂+喷涂打底涂层、喷砂+电拉毛这3种工艺对QSTE420TM钢板进行表面预处理,之后采用相同工艺进行电弧喷涂4Cr13涂层,分析了涂层组织和断口形貌,测试了涂层的显微硬度和结合强度,对比了3种预处理工艺对涂层组织和性能的影响.结果表明:电弧喷涂4Cr13涂层组织呈现出典型的层状结构;不同的表面预处理工艺对涂层的结合强度影响显著,喷砂粗化+喷涂打底涂层能使4Cr13涂层获得最优的综合性能.     

Electrospark alloying for deposition on aluminum surface of Al-Sn coatings and their wear resistance under dry friction

Some aspects of coating deposition on aluminum substrate by electrospark alloying with toolelectrode from Al-Sn alloy stimulating the SnO₂ nanofibers formation in coatings have been studied. Wear resistance of such coatings, under dry friction conditions, in conjunction with a counterbody from hardened steel has been investigated. The conditions under which the coatings thus obtained manifest the of effect of the maximal wear excess of the counterbody compared to the wear of the coatings containing SnO₂ nanofibers have been specified. The effect reaches its maximum value under the dry friction after the treatment of the surface in the mode of “sparking” at a constant energy supply in the spark gap: at high rates of the tool electrode movement with respect to the specimen and at relatively large times of the electrospark effect on the treated surface.     

脉冲放电熔涂Cr2B表面强化工艺及强化层组织性能研究

本文采用新型脉冲放电电火花表面强化设备,以Ｃｒ２Ｂ作为电极材料,研究了热作模具钢电火花表面强化工艺及强化层质量,分析了强化层组织结构的特点及强化层性能。研究结果表明,Ｃｒ２Ｂ电极强化层具有表面质量好、强化层厚和硬度高等特点,是一种高性能的表面强化涂层     

Preparation and mechanical properties of two nickel base alloy coatings achieved by electrospark deposition

Ni398 and Ni818 base alloy coatings were deposited on 1045 steel by electrospark deposition technique (ESD). Forming properties, thickness, microhardness and wear resistance of the coatings were investigated. The chemical composition and crosssection morphology were analyzed through energy dispersive spectrum (EDS) and metalloscope. The results show that the technological parameter window of Ni398 is larger than that of Ni818 electrode. However, other properties of the Ni818 coating, such as thickness and m...     

The development of criteria for evaluating the effectiveness of the surface layer formation and its properties in the process of electrospark alloying (ESA). Part 2. The criteria of the effectiveness of the ESA process and electrospark coatings

The paper offers comprehensive and integrated specific criteria for the effective use of electrospark alloying (ESA) to determine the effectiveness of the conditions of applying electric-spark coatings with the required performance characteristics and parameters of the surface topography, taking into account the energy costs. A general criterion is also provided for the efficiency of the coating, allowing us to determine and compare the performance of different coating processes by ESA and other methods based on energy consumption, and economic and environmental factors.     

Surface hardening of Fe-based alloy powders by Nd：YAG laser cladding followed by electrospark deposition with WC-Co cemented carbide

This paper presents the results of a study concerned with the surface hardening of Fe-based alloys and WC-8Co cemented carbide by integrating laser cladding and the electrospark deposition processes. Specimens of low carbon steel were processed firstly by laser cladding with Fe-based alloy powders and then by electrospark deposition with WC-8Co cemented carbide. It is shown that, for these two treatments, the electrospark coating possesses finer microstructure than the laser coating, and the thickness and surface hardness of the electrospark coating can be substantially increased.     

电火花沉积非晶涂层的组织结构与摩擦磨损性能

以Zr₅₅Al₁₀Ni₅Cu₃₀非晶态合金棒为电极,利用电火花沉积技术在ZL101铝合金表面制备了锆基合金涂层.利用X射线衍射仪（XRD）、扫描电镜（SEM）、显微硬度计和摩擦磨损实验机等对涂层的微观结构、表面形貌、显微硬度和摩擦磨损性能进行了分析测试.结果表明,沉积层表面较致密、均匀,为典型的“溅射状”花样形貌;沉积层主要由非晶、ZrO₂和Cu₈Zr₃等相组成;沉积层的平均显微硬度为1 555 HV 0.01,约为基材的15倍,摩擦系数仅为0.096,呈现出良好的减摩耐磨特性,沉积层的磨损机制主要为疲劳磨损和磨粒磨损.     

电火花沉积Ni基涂层的质量过渡及电极损失

采用逐层沉积的方法,在基材表面获得了1-8层Ni基电火花涂层,探讨了电火花沉积过程中Ni基电极的质量过渡规律及电极材料的流失形式。结果表明:Ni基电极向基材的平均质量过渡系数为0.76;电极的损失有气化、液态溅射和氧化三种形式;氩气保护在沉积过程中起重要作用;随着沉积层厚度的增加,基材对涂层的稀释越来越小。     

Interface behavior study of WC92-Co8 coating produced by electrospark deposition

ESD (electrospark deposition) is a promising process to produce hard and wear-resisting coatings on metallic substrates. In this paper microstructure and inteorucial characteristics of the WC92-Co8 coated on titanium and carbon steel are presented. A metallurgical bonding between the coating and substrate is obtained. The Ti element was found to distribute in WC92-Co8 at the metal pool, as well as the interface by diffusion. Some new phases were produced in the coating layer due to the chemical reaction during the ESD process. Experimental observation and thermodynamic analysis were utilized to study the mechanism of ESD.     

Investigation of coatings produced by the electrospark machining method of steel 45 with electrodes based on carbides of tungsten and titanium

The article is devoted to the development and investigation of tungsten-containing and tungstenless electrode materials for electrospark alloying using additives of boron-containing minerals, as well as aluminum-oxide nanopowder. The kinetics of the mass transfer process with the electrospark alloying of coatings was investigated. The phase composition, roughness, and kinetics of high-temperature oxidation of coatings were studied. The anticorrosive properties of obtained coatings were studied in 3% NaCl solution by the method of impedance spectroscopy. An improvement of the barrier properties of TiC–Ni–Mo coatings with increasing datolite concentrate was revealed.     

Optimization of the composition, structure, and properties of electrode materials and electrospark coatings for strengthening and reconditioningof metal surfaces

The structure and phase composition of Ni-Cr-Al alloys doped with Si, Ti, Mn, and Co have been studied. An eutectic three-phase structure was found to be in the doped alloys. Doping with Si and Ti increases the microhardness and wear resistance of the alloys. The highest coefficient of the mass transfer (0.75) during the electrospark alloying is observed for Co-containig alloys. The coatings with the doped alloys have a higher wear resistance than those with the Ni-Cr-Al basic alloy. Steel 45’s heat resistance is increased after the electrospark doping with Si-, Ti-, Mn-, and Co-containing alloys by 4, 4.3, 5.1, and 4.6 times, respectively. The electrode materials have been developed for the electrospark reconditioning of workpieces based on PE8418 (Ni-Ni₃B-Cu-Si) with the additions of titanium carbide, chromium carbide, and tungsten carbide, which make it possible to manufacture coatings up to 5-mm thick. The results of the investigation of the erosion properties of B₄C-TiB₂ alloys manufactured using the method of reactive sintering under hot pressing of B₄C-TiO₂ powder blends that were used as the electrode materials for the electrospark hardening of titanium surfaces are presented. The tests show that, in the surface layers of the electrode materials, under the impact of the electric discharge, the boron carbide content substantially decreased, while the quantity of titanium borides increased and new phases of TiC _x N _y , TiO₂, and Ti appeared. Only these components are transferred onto the surface of the titanium alloy and form there a protective coating up to 100 μm thick with high hardness (32–43 GPa) and wear resistance. The materials developed are promising for their application as the electrodes in the electrospark alloying of construction steels and titanium alloys.     

Features of plastic deformation of electrospark coatings and ways for improvement of their strength characteristics at friction

Analysis of the structural state of surface metal layers after their electrospark doping (ESD) and subsequent surface plastic deformation (SPD) has been performed. The structure levels and their scale ranging within 20–10³ nm have been determined. Applying the methods of X-ray structure analysis and electron microscopy, it has been found that the linear defect density after ESD and after ESD + SPD is practically identical; this allowed suggesting that the basis for the mechanism of plastic deformation of electrospark coatings is collective motion of dislocations, that is, rotational processes. Some ways of formation of stable and more homogeneous structures of electrospark coatings with required properties have been analyzed and proposed.     

Formation of composite coatings based on titanium carbide via electrospark alloying

This work concerns studying the coatings prepared via electrospark alloying. To deposit the coatings, we used STIM-2/30 electrodes derived from a combination of self-propagating high-temperature synthesis (SHS) and extrusion. It was found that the composite coating is formed from titanium carbides and a solid solution of nickel in iron and contains both large (4–5 μm) and small carbides (less than 1 μm); in addition, large grains of titanium carbide are formed in the central portion of the coating, and the grain size decreases to 100 nm while approaching the transition zone. Large grains of titanium carbide in the coating consist of dispersed carbides with sizes less than 1 μm. It is determined that the composition of the substrate has an effect on the size of the transition and diffusion zones. It ranges from 17 μm for steel 9KhSA to 26 μm for steel 20; that is, the higher the degree of alloying, the less the depth of the modified layer.     

Reasons for restricting the thickness of electrospark coatings and methods for increasing their thickness

The problem of increasing the thickness of electrospark coatings is studied. The published studies dealing with the reasons for restriction of the thickness of the coatings and methods for increasing this thickness are analyzed.     

Materials for the electrospark strengthening and reconditioning of worn metal surfaces

The aim of this work is the development of technology for obtaining electrode materials from Colmonoy-WC alloys and hard alloys containing TiC, WC, Mo₂C, Tin, Co, Cr, Ni, and Al. The phase composition and structure are studied along with the kinetics of mass transfer, hardness, and wear resistance of electrospark coatings made of the manufactured alloys. The methods used were metallography and electron microscopy and X-ray phase and durometric analyses. It was shown that the alloys Colmonoy (Ni-Ni₃B–Si–Cu), Colmonoy-10% WC, and Colmonoy-25% WC have a eutectic structure. With an increase in the WC content in the alloys, the structure is found to be an aggregation of the phases of a hard solution based on nickel and tungsten carboborosilicide. At the pulse energy of 7.5 J, the thickness of the coatings formed was 3–4 mm. The wear resistance of the coatings increased with the growth of the WC content in the coatings from 64.5 μm/km for Colmonoy to 18.5 μm/km for the alloy with 70% WC, and the steel wear resistance under those conditions was 160 μm/km. It was established that the structure and composition of the manufactured electrode materials from the hard alloys based on TiC and WC carbides make it possible to produce electrospark coatings with a thickness up to 100 μm and hardness up to 20–24 GPa. The developed materials can be used to harden/recondition worn workpieces made of constructional steels by the electrospark method.     

Influence of electrospark discharge parameters on roughness and microabrasive wear of steel 45 surface after ESA by TiC-based electrodes

The influence of the parameters of electrospark discharge and electrode materials for electrospark alloying using the additives of boron-containing mineral raw material on the characteristics of microgeometry and microabrasive wear of the coating surface is investigated. It is found that the longer is the electrospark duration (from 20 to 80 μs), the higher is the surface roughness. The introduction of 1–2% of boron-containing raw material improves physicochemical properties of the alloyed layer, reduces the roughness, and increases the wear resistance.     

Effect of electrode material on formation of electrospark coatings on cutting tools and equipment parts

The effect of the material of the alloying electrode on formation of electrospark coatings on blade cutting tools and equipment parts produced from high-speed steel is studied.     

几种电火花熔涂层的腐蚀性能研究

对正火45钢基体上的Cr、W、Mo和Ni电极电火花熔涂层在水、5vol%盐酸及硝酸水溶液中的腐蚀行为进行了研究.结果表明，熔涂层的抗腐蚀能力，在水中，优于正火45钢，但在酸性介质中，比正火45钢的抗腐蚀能力还差.熔涂层腐蚀破坏的主要机理是成分和组织不均匀引起的电化学腐蚀和局部腐蚀，最终导致熔涂层剥落.      

On electrodeposition of thick coatings of increased continuity

This article is devoted to the currently important problem of increasing of the thickness of electrodeposited coatings with higher contact continuity. The results of experiments on the formation of thick coatings of increased continuity on a steel surface using electrodes of Kh20N80 alloy, ShKh15 steel, and BrKMts3-1 bronze are given. The basis of the treatment is the alternation of the deposition and melting operations performed by electrospark machining (ESM).