Properties of Al2O3 nano-particle reinforced copper matrix composite coatings prepared by pulse and direct current electroplating

Cu–Al₂O₃ nano-composite coatings have high potential for use in applications in which high mechanical properties together with high corrosion resistance are required. In the present study it is intended to produce copper nano-alumina composite coatings with various nano-alumina contents in order to investigate the effect of alumina reinforcement particles on corrosion resistance and mechanical properties such as hardness and wear resistance. The composite coatings were deposited using direct current (DC) and pulse current (PC) plating. The microstructures of the coatings produced from both methods were examined via scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The wear behaviors, micro hardness, coating thickness, corrosion rate and coating porosity were examined using appropriate methods. Compared to DC deposition, PC plating facilitated higher amounts of particle incorporation with more uniform distribution. The results indicated that the mechanical properties of the applied coatings with incorporated nano-alumina reinforcement were far more superior as compared to its own matrix as well as non-composite copper coatings. It was also found out that increasing the amount of nano-alumina content in the coating, led to enhanced general properties of the coatings.     

Effect of substrate bias voltage on structural and mechanical properties of pulsed DC magnetron sputtered TiN-MoSx composite coatings

TiN-MoS_x composite coatings were deposited by pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS) using separate Ti and MoS₂ targets in an Ar and N₂ gas environment. The effect of substrate bias voltage on the structure and mechanical properties of TiN-MoS_x composite coating has been studied. The structure and composition of the coating were evaluated using field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) by X-ray and grazing incidence X-ray diffraction (GIXRD). Scratch adhesion tests, Vickers microhardness tests and ball-on-disc tests with a cemented carbide (WC-6%Co) ball were carried out to investigate mechanical properties of the coating. Application of substrate bias was found to transform the structure of TiN-MoS_x composite coating from open columnar to a dense columnar structure. The changes in grain size and texture coefficient appear to be associated with variation in substrate bias voltage. The mechanical properties of the coating such as adhesion and composite microhardness were also observed to be related to the change in bias voltage. A maximum hardness of 22 GPa was obtained for a coating deposited at substrate bias voltage of −40 V. The improved structural and mechanical properties of the coating deposited at −40 V were also reflected in its excellent wear resistance property.     

Effects of TIG surface treating on microstructural characteristics and mechanical properties of Al2O3–TiB2 coating by APS

Abstract

The pulsed DC tungsten inert gas (TIG) method was employed to post-spray treat an electroconductive Al₂O₃–TiB₂ coating by atmosphere plasma spraying (APS) Al₂O₃–30 wt-%TiB₂ powder. The microstructure and mechanical properties of the coatings before and after treatment were comparatively investigated by scanning electron microscopy, laser scanning confocal microscopy, X-ray diffraction, microhardness tester and block on ring wear tester. It was detected that the treated coating presented a two layer structure consisting of the remelted zone and the sintered zone, which was comprised of TiB₂ and single α-Al₂O₃; surface roughness of the treated coating exhibited a remarkable decrease while microhardness and wear resistance showed a significant increase. These experimental results could be ascribed to the effect of high heat input and discharge plasma during the pulsed DC TIG treating.     

Microstructure and characterization of Ni-Co/Al2O3 composite coatings by pulse reversal electrodeposit

Ni-Co/Al₂O₃ composite coatings were obtained by pulse reversal electrodeposit (PRC) and direct current electrodeposit (DC). The microstructure of the coatings was characterized by means of SEM, XRD and TEM. Hardness, wear resistance and macro residual stress of coatings were also investigated. The results showed that the microstructure and performance of the coatings were significantly affected by the electrodeposit methods and the Al₂O₃ particles content. The PRC composite coatings exhibited compact surface, high hardness and excellent wear resistance. The macro residual stress of PRC composite coatings was lower than that of DC ones. With the increasing of Al₂O₃ particles content, the hardness and wear resistance of the composite coatings increased.     

石墨烯/纳米Al2O3增韧Ti(C,N)基金属陶瓷的力学及摩擦磨损性能

采用真空热压烧结工艺制备了石墨烯(GNPs)和纳米Al₂O₃增韧的Ti(C,N)基金属陶瓷复合刀具材料(TAG)。研究了GNPs和纳米Al₂O₃对复合陶瓷材料微观结构、力学性能和摩擦磨损性能的影响。研究表明,GNPs和纳米Al₂O₃的添加对复合陶瓷材料的力学性能有明显的提高,当GNPs和纳米Al₂O₃含量(质量分数)为1%和5%时,复合刀具陶瓷材料(TA5G1)综合力学性能最优,其硬度、抗弯强度和断裂韧性分别为21.50 GPa、810.80 MPa和10.51 MPa·m^1/2。研究了复合刀具材料的摩擦磨损性能和磨损机理,研究结果表明,在TAG复合刀具材料中,TA5G1的摩擦磨损性能最优,其摩擦系数和磨损率分别为0.338和4.921×10^-6 mm³/(N·m),复合刀具材料的主要磨损形式为磨粒磨损和黏着磨损。     

工艺参数对脉冲电沉积Ni-TiN纳米镀层微观组织和性能的影响

电沉积技术是一种方便、高效、低成本制备金属基纳米镀层的方法,其工艺参数直接决定金属基纳米镀层的微观组织及性能。为系统研究电沉积工艺参数对金属基纳米镀层表面形貌、显微组织、力学性能及耐磨损性能的影响规律,本实验采用脉冲电沉积制得Ni-TiN纳米镀层,并利用透射电镜(TEM)、原子力显微镜(AFM)、X射线衍射仪(XRD)、摩擦磨损试验机研究了工艺参数对Ni-TiN纳米镀层的显微结构、显微硬度和性能的影响。结果表明,当电流密度为4A/dm~2时,Ni-TiN纳米镀层的显微硬度为984.7HV,TiN微粒复合量为8.69%(质量分数)。采用不同脉冲频率制得的Ni-TiN纳米镀层,其晶面原子呈现不同方向的面心立方晶格结构。当脉冲频率为200Hz时,Ni-TiN纳米镀层中Ni和TiN的平均粒径分别为87.2nm和34.6nm。当脉冲占空比为20%时,Ni-TiN纳米镀层的显微硬度为980HV,其平均磨损量为7.56mg/mm2。     

Cr3C2 incorporation into an Inconel 625 laser cladded coating: Effects on matrix microstructure,mechanical properties and local scratch resistance

There is an increasing industrial demand for metal alloys with high wear resistance under severe operating conditions. Ni-based alloys, such as Inconel superalloys, are an excellent option for these applications; however, their use is limited by their high cost. Ni-based coatings deposited onto carbon steel substrates are being developed to achieve desired surface properties with reduced cost. Laser cladding deposition has emerged as an excellent method for processing Ni based coatings. In this work, microstructure, mechanical properties and local wear behaviour have been investigated in response to the addition of Cr₃C₂ ceramic particles into an Inconel 625 alloy deposited onto a ferritic steel substrate by laser cladding. Using this deposition technique, a homogeneous distribution of Cr₃C₂ particles was observed in the coating microstructure. The addition of ceramic particles to the starting powder resulted in the formation of hard precipitates in the coating microstructure. The partial dissolution of Cr₃C₂ particles during the laser cladding process increased the hardness of the Inconel 625 matrix. Depth sensing indentation and scratch tests were performed to study the local wear behaviour and scratch resistance of the cermet matrix compared with the conventional Inconel 625 alloy. Finally, the effect of Cr₃C₂ on mechanical properties was correlated with the observed microstructure modifications.     

Pulse and direct electrodeposition of Ni–Co/micro and nanosized SiO2 particles

Ni–Co/SiO₂ composite coating was electrodeposited on the steel substrate. The coatings were characterized by X-ray diffraction and scanning electron microscopy. The microhardness of the composite coatings was studied by variation of the electroplating parameters, such as the pulse current (PC) and direct current (DC) electrodeposition methods, deposition temperature, electrolyte pH, concentration of surfactants, sodium dodecyl sulfate (SDS), and cetyltrimethylammonium bromide (CTAB). Zeta potential of SiO₂ particles measurements was performed with various pH, SDS, and CTAB concentrations. The data depict that the hardness of Ni–Co/SiO₂ nanocomposite coatings manufactured by PC electrodeposition increases with the increase of bath temperature, pH, SDS, and CTAB concentration up to 50°C, 4.6, 0.3, and 0.2?g/L, respectively. Beyond mentioned optimum values, the microhardness of nanocomposite coating decreases. Using DC method led to reduce the microhardness. Utilizing SiO₂ microparticles instead of SiO₂ nanoparticles for reinforcing resulted in declining the microhardness. The friction coefficient and wear results demonstrated that using PC method and nanosized particles led to reduce the friction coefficient and increase the resistance to wear. Anodic polarization results illustrated that using SiO₂ nanoparticles and PC method to prepare coating caused corrosion resistance of coating in a 3.5?wt% NaCl solution to enhance.     

Wear behaviors of Fe-based amorphous composite coatings reinforced by Al2O3 particles in air and in NaCl solution

In this paper, the influence of the addition of Al₂O₃ particles on the microstructure and wear properties of Fe-based amorphous coatings prepared by high velocity oxygen fuel (HVOF) has been studied. The wear behaviors of the composite coatings were evaluated against Si₃N₄ in a pin-on-disk mode in air and in 3.5 wt.% NaCl solution. It was found that the Al₂O₃ particles were homogenously distributed in the amorphous matrix and the composite coatings exhibited improved wear resistance and reduced coefficient of friction (COF) in both air and wet conditions as compared to the monolithic amorphous coating. The composite coating reinforced with 20 wt.% Al₂O₃ particles exhibit the best wear performance, which, for example, has extremely low COF (< 0.2) and high wear resistance (2–3 times higher than monolithic amorphous coating). Detailed analysis on the worn surface indicated that the wear mechanism for the amorphous and composite coatings is similar and is dominated by oxidative delamination in air and by corrosion wear in 3.5% NaCl solution. The enhanced wear resistance is mainly attributed to the addition of Al₂O₃ particles which exhibit high hardness, good corrosion resistance and excellent chemical and thermal stability.     

Tungsten/tungsten nitride performance at elevated temperature

Abstract

Multilayer physical vapour deposition (PVD) coating of W/W₂N (tungsten/tungsten nitride) on Orvar Supreme steel was tested under the different conditions to investigate their friction and wear behaviour with their mechanical properties. Coatings were sputtered by reactive magnetron sputtering in a N₂/Ar atmosphere. Pin on disc test was performed on Orvar Supreme steel at room temperature to elevated temperature (800°C). Steel ball (100Cr6) and alumina ball are used to evaluate the frictional and wear properties. Scanning electron microscopy (SEM) and energy dispersive X-ray analyses were performed to obtain the microstructure and chemical composition of the material. Mechanical properties of coating were evaluated using nanoindentation and scratch test.     

用于纤维材料表面耐磨涂层的制备与性能表征

为使涤纶织物应用范围更广,更耐磨,本文制备了一种有机硅树脂基纳米硼化钛碳化钛复合涂层,通过正交实验法得到最佳的涂层方案,并尝试将其应用于涤纶织物,以改善涤纶织物的表面结构,进而实现涤纶织物表面优异的耐磨性能.为测试涂层对涤纶织物性能的影响, 采用泰伯式耐磨仪、液滴形状分析仪、电子织物强力机、扫描电子显微镜(SEM)研究了涂层织物的耐磨性能、疏水性能、物理机械性能和磨损织物的表面微观形态.研究表明：当有机硅树脂与无水乙醇质量比为75: 25,含量(质量分数)为93%;超分散剂含量为1.5%;乙醇增稠剂含量为1.5%;纳米硼化钛和碳化钛质量比为2: 1,含量为4%时,所得涂层溶液应用于涤纶织物后会形成一层包覆层,耐磨性能最优.对于涂覆量为15 g/m²的涤纶,拉伸断裂强力由573.92 N提高到620.48 N,顶破强力由652.34 N提高到790.07 N,撕裂强力由9.87 N降低到5.78 N,疏水性能有较大提高,接触角可达到120°以上.     

The microstructure and wear resistance characteristics of electroformed nickel and partially stabilized zirconia composite coatings

Ni-PSZ composite coatings with various PSZ particle content were prepared by the electroforming technique. The microstructure and surface components of the coatings have been examined by optical microscopy, electron microscopy and X-ray photoelectron spectroscopy analysis and the wear properties of the coatings tested on a reciprocating wear test machine. The results show that the PSZ particles are uniformly dispersed in the coatings and thus increase the wear resistance of the coatings by inhibiting plastic deformation of the nickel matrix. The co-deposition of the PSZ particles in the electrolyte is mainly in the form of agglomeration and is accompanied by the incorporation of Ni(OH)₂. When the PSZ content in a coating is higher than a critical value, the wear resistance of the coating could deteriorate because of the decrease in the integrity of the nickel matrix. After heat-treatment at high temperature, Ni(OH)₂ in the coating is turned into Ni₂O₃ and NiO which can wet the PSZ particles and increase the bonding strength between the PSZ and nickel. In addition, the agglomerated PSZ particles are sintered when heat-treated. These are all beneficial to increasing the wear resistance of the coating.     

Microstructure of direct current and pulse magnetron sputtered Cr-B coatings

Chromium diboride thin films possess desirable combinations of properties (such as high hardness, wear resistance, chemical inertness, high thermal and electrical conductivity), which are attractive for a wide range of potential industrial applications. However, these properties depend strongly on the deposition process and parameters. Investigation of the resultant coating structures could explain certain differences between them, giving important information about the characteristics of the deposition process (which in this particular case is a recently developed method involving magnetron sputtering of loosely packed blended powder targets) and pointing out directions for improvement.In this paper, Cr-B coatings deposited by direct current (DC) and DC-pulse magnetron sputtering of loosely packed blended powder targets are characterised by transmission electron microscopy (TEM) techniques (electron diffraction and bright-field/dark-field imaging). The structures of the coatings deposited with different parameters are investigated and compared, and the effect of oxygen contamination on the structure is discussed.Coatings with an extremely fine, nanocolumnar structure were observed. DC sputter deposited (and generally non-stoichiometric) Cr-B coatings exhibit a short range ordered ‘zone T’ microstructure, while DC-pulse deposited stoichiometric CrB₂ coatings are dense and defect-free, crystalline and show strong preferred orientation.A small amount of contamination by oxygen of the interfacial sub-layers (due to the target material being a powder) of the DC-pulse magnetron sputter deposited stoichiometric CrB₂ (and near-stoichiometric CrB) coatings was found to affect the structure by suppressing nanocolumnar growth and promoting equiaxed, nanometer-sized grains, close to the coating/substrate interface. The majority of the coating however remained nanocolumnar.     

Microstructure,mechanical and erosion wear analysis of post heat treated iron alloy based coating with varying chromium

The present work focuses on the effect of annealing heat treatment on the microstructure, mechanical and erosion properties of iron alloy based coatings with varying chromium content. High velocity oxygen fuel coating method was used to deposit the coating over the substrate material 316 L stainless steel. The study was done in terms of microstructural analysis using x-ray diffractometer, surface and cross-sectional morphology using field emission scanning electron microscope, mechanical and erosion wear analysis. It was found that x-ray diffractometer indicated presence of less amount of titanium dioxide (TiO₂) and silicon dioxide (SiO₂) after heat treatment. However, the peaks of hardened phase of diironylidenetitanium (Fe₂Ti) and iron-chromium (Fe−Cr) was increased. Addition of chromium up to 10 wt. % improved the hardness and adhesion pull of strength by 16 % and 62 % respectively. On the other side heat treatment of iron alloy based coating having 10 wt. % chromium increased the hardness and adhesion pull off strength by 17.3 % and 35 % respectively. The erosion wear rate was also decreased with the annealing process. The study shows that the annealing process increases hardness and adhesion pull off strength but decreases porosity and erosion wear rate.     

Synthesis and characterization of functionally graded nickel‐nickel coated ZrO2 composite coating

Electroless‐nickel plated ZrO₂ (NCZ) particles have been used to produce a functionally graded nickel‐electroless‐nickel plated ZrO₂ composite coating. So, electroless‐nickel plated ZrO₂ particles concentration was continuously increased from 0 to an optimum value in the electroplating bath (Watt's bath). The substrate was ST37 steel and the thickness of the coating was approximately 50 μm. Also a uniformly distributed nickel‐electroless‐nickel plated ZrO₂ composite coating has been manufactured as comparison. The composite coatings were characterized by scanning electron microscopy and energy‐dispersive X‐ray spectroscopy. Structure and phase composition were identified by X‐ray diffraction analysis. Microhardness of the coatings was evaluated by employing a Vickers instrument. Three‐point bend test was carried out to compare the adhesion strength of the coatings. Dry sliding wear tests were performed using a pin‐on‐disk wear apparatus. The electrochemical behavior of the coatings was studied by electrochemical impedance spectroscopy. The microhardness measurements showed that, with increasing the co‐electrodeposited electroless‐nickel plated ZrO₂ particle content in the nickel matrix, the microhardness increases from interface towards the surface of the functionally graded composite coating. Bend, wear and electrochemical test results confirmed that the functionally graded composite coating has higher adhesion, wear resistance and corrosion resistance as compared with the uniformly distributed coating. This has been attributed to lower mechanical mismatch between coating and substrate in functionally graded composite coating with respect to the uniformly distributed one.     

(Mg2B2O5w+ND)/ZK60镁基复合材料的摩擦磨损性能研究

在湿球磨条件下以600 r/min高能球磨混粉,并将球磨后的粉末经过热压烧结-热挤压成型制备(Mg2B2O5w+ND)/ZK60镁基复合材料。研究了(Mg2B2O5w+ND)/ZK60镁基复合材料在不同载荷和转速下的干摩擦磨损性能。结果表明:干摩擦条件下,材料的摩擦系数随着滑动距离的增加会经历跑和阶段和稳定阶段;材料的质量磨损率随着转速的增大而降低,随着载荷的增大而增大,且基体镁合金的质量磨损率始终低于复合材料。随着摩擦载荷和转速的增加,材料的摩擦系数减小,然后逐渐趋于平稳。混杂增强的镁基复合材料相比基体合金具有更低的摩擦系数。     

Microstructure and mechanical characteristics of iron-based coating prepared by plasma transferred arc cladding process

This paper investigated the effect of electromagnetic stirring (EMS) on the microstructure and abrasive wear behavior of iron-based coatings. A series of coatings were prepared by using plasma transferred arc cladding (PTAC) process. The phase and structure of the coatings were characterized by means of SEM, EDXA and X-ray diffraction. The microstructure of the coatings was mainly γ-Fe matrix and (Cr, Fe)₇C₃ carbide reinforced phases. Without EMS, the average size of (Cr, Fe)₇C₃ carbide was about 73 μm, while that of the carbide reached a minimum value of about 20 μm with stirring current of 3 A. The mechanical properties, especially wear resistance, were analyzed in detail. The results showed that the microstructure of the coating plays an important role on abrasive mechanism and the main mechanism is micro-cutting. When the stirring current is 3 A, the coating exhibits excellent wear resistance, which contributes to the good microstructures that hexagonal (Cr, Fe)₇C₃ carbide with the highest volume fraction are uniformly distributed in the matrix. The microhardness of the coatings increase at first, and then decrease as a function of stirring current. The maximum microhardness value of the coating is about 1050 HV.     

Effect of alumina particle size and thermal condition of casting on microstructure and mechanical properties of stir cast Al–Al2O3 composites

Abstract

Metal matrix composites are considered as a distinct category of the advanced materials, which have low weight, high strength, high modulus of elasticity, low thermal expansion coefficient and high wear resistance. Among them, Al–Al₂O₃ composites have achieved significant attention due to their desired properties. In the present research, Al–Al₂O₃ composites with 5 vol.-% alumina were produced by stir casting at a temperature of 800°C. Two different particle sizes of alumina were used as 53–63 and 90–105 μm. The microstructure of the samples was evaluated by SEM. In addition, the mechanical properties of the samples were measured, and hence, the optimum temperature and particle size of alumina to be added to the Al matrix were determined. The results demonstrated the positive effect of alumina on improving the properties of Al–Al₂O₃ composites.     

Pulse electric current sintering of alumina/nickel nanocomposites

Typical magnetically functionalized Al₂O₃/Ni nanocomposite materials were fabricated by pulse electric current sintering process. The rapid densification and various microstructures were accomplished with controlling PECS temperature. The PECSed Al₂O₃/Ni system exhibited peculiar mechanical and magnetic properties with microstructure developments. The mechanical properties of Al₂O₃/Ni nanocomposite were optimized as controlling microstructures, and fine metal dispersion into the Al₂O₃ matrix give to the various ferromagnetic properties. Electronic Publication     

Pulse plating of Ni–B/WC nanocomposite coating and study of its corrosion and wear resistance

The aim of this study is to investigate the impact of WC content on the properties of the Ni–B/WC nanocomposites deposited by the pulse method. It is obtained that, although by addition of WC nanoparticles to the bath in initial steps (WC 4 and 8 g?l^?1), the grain size was increased and hence mechanical and electrochemical properties got worse, but at the higher amount of WC (WC 12 g?l^?1), due to the formation of the fine and packed structures, the great corrosion and wear resistance was achieved. The corrosion resistance of the Ni–B/WC12 g?l^?1 coating is 59,967?Ω and wear weight loss is 2.1 mg?cm^?2 with the friction coefficient of 0.64.