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1.
Ni-Al2O3 composite coatings were prepared by using sediment co-deposition (SCD) technique from a Watt's type electrolyte containing nano-Al2O3 particles. The corrosion resistance and high temperature oxidation resistance of resulting composite coatings were investigated. It was found that the incorporation of nano-Al2O3 particles in Ni matrix refined the Ni crystal and changed the preferential orientation of composite coatings. Meanwhile, the corrosion and oxidation resistance were improved after the incorporation of nano-Al2O3 particles into Ni matrix. The nano-Al2O3 content in deposits plays an important role for improving the corrosion and oxidation protection. The corrosion and oxidation resistance of Ni-Al2O3 nano-composite coatings produced via SCD technique are superior to that of CEP technique. Compared to pure Ni and Ni-Al2O3 composite coatings fabricated using CEP technique, the Ni-7.58 wt.% Al2O3 composite coating obtained by SCD technique exhibits better corrosion resistance and enhanced high temperature oxidation resistance. Moreover, the mechanism of corrosion and high temperature oxidation resistance of Ni-Al2O3 nano-composite coatings are discussed. 相似文献
2.
Nano-sized Al2O3 ceramic particles (50 nm) were co-deposited with nickel using electrodeposition technique to develop composite coatings. The coatings were produced in an aqueous nickel bath at different current densities and the research investigated the effect of applied current on microstructure and thickness of the coatings. The variation in some mechanical properties such as hardness, wear resistance, and the adhesive strength of the composite coatings is influenced by the applied current and this was also studied. The morphology of the coatings was characterized by scanning electron microscopy and energy dispersive X-ray spectroscopy. The hardness, wear resistance, and bond strength of the coatings were evaluated by Vickers micro-hardness test, pin-on-disc test, and tensile test, respectively. Results showed that the Al2O3 particles were uniformly distributed in the coatings, and the coatings deposited at a current density of 0.01 A/cm2 was most favorable in achieving a maximum current efficiency which causes the co-deposition of a maximum amount of Al2O3 particles (4.3 wt.%) in the coatings. The increase in Al2O3 particles in the coatings increased the mechanical properties of the Ni-Al2O3 composite coatings by grain refining and dispersion strengthening mechanisms. 相似文献
3.
Previous studies have shown that the fabrication of metal matrix composites (MMCs) by cold spraying is effective and promising. When light materials, such as SiC and Al2O3, were used as reinforcements, it was diffcuclt to obtain a high volume fraction of hard phase in the composite just through the simple powder mixture. Therefore, in this study, a Ni-coated Al2O3 powder, which was produced through hydrothermal hydrogen reduction method, was employed aiming at increasing the volume fraction of ceramic particles in the deposited composite coating. It was found that a dense Ni-Al2O3 composite coating could be deposited with the Ni-coated Al2O3 powder under the present spray conditions. X-ray diffraction analysis indicated that the composite coating had the same phase structures as the feedstock. The volume fraction of Al2O3 in the composite was about 29 ± 6 vol.%, which is less than that in the feedstock (nominal: 40-45 vol.%) due to the rebound of some Al2O3 particulates upon kinetic impacting. The microhardness of the composite coating was about 173 ± 33Hv0.2. 相似文献
4.
Qiuyuan Feng Tingju Li Zhongtao Zhang Jian Zhang Mei Liu Junze Jin 《Surface & coatings technology》2007,201(14):6247-6252
Ni/Al2O3 composite coatings were prepared by a novel method from a modified Watt's type electrolyte containing nano-Al2O3 particles, where a high magnetic field was imposed in the direction parallel to an electrolytic current instead of mechanical agitation. Effects of magnetic field on the content of particles, surface morphology, microhardness and wear resistance of plating layer were investigated. It was found that the high magnetic field played an important role in the formation of composite coatings. The amounts of nano-Al2O3 particles in the composite coating increased with increasing of magnetic flux density and reached a maximum value at 8 T, then reduced slightly. The microhardness and wear resistance of the nanocomposite coatings also enhanced with increasing of magnetic flux density as compared to that of pure Ni coating fabricated in the absence of magnetic field. That was because the co-deposited nano-Al2O3 particles were uniformly distributed in the Ni matrix and contributed to greatly increase the microhardness and wear resistance of the composite coatings. Moreover, the mechanism of action of high magnetic field was discussed preliminarily. 相似文献
5.
采用复合电沉积法在304奥氏体不锈钢表面制备Ni-Al2O3纳米镀层. 研究了Al2O3颗粒在复合镀层中的分布情况, 确定了镀液中颗粒的最佳加入量、最佳电流强度和最佳搅拌速度. 用扫描电镜和能谱仪、X射线衍射仪等设备鉴定镀层显微组织与组成. 结果表明, Ni-Al2O3纳米复合镀层均匀、致密、晶粒细小; 复合镀层结合强度、耐腐蚀性能优良, 抗高温氧化性能优于纯镍镀层. 相似文献
6.
E. Sánchez A. Moreno M.D. Salvador E. Klyatskina R. Moreno 《Surface & coatings technology》2010,205(4):987-992
Al2O3-TiO2 coatings were deposited on austenitic stainless steel coupons from nanostructured powders by atmospheric plasma spraying (APS). Commercial suspensions of nanosized Al2O3 and TiO2 particles were used as starting materials. Mixtures of these suspensions and of more concentrated suspensions of Al2O3 and TiO2 were then agglomerated into plasma sprayable feedstock. Agglomeration was performed by spray drying, followed by consolidation thermal treatment.These powders were successfully deposited, yielding coatings that were well bonded to the substrates. The coating microstructure thus consisted of semi-molten feedstock agglomerates surrounded by fully molten particles that acted as binders. Agglomerates from suspensions with higher solids contents yielded coatings with lower porosity and fewer semi-molten areas. 相似文献
7.
《金属精饰学会汇刊》2013,91(4):181-187
AbstractThis paper presents results of a research on the corrosion resistance of composite Ni/Al2O3 coatings electrochemically deposited from Watts baths containing different amounts (0, 20, 100 g dm?3) of Al2O3 particles. Potentiodynamic tests and electrochemical impedance spectroscopy (EIS) measurements were carried out in a 3% solution of NaCl. The coatings with about 6 wt-% of corundum, deposited from a bath with 100 g dm?3 of a powder, showed the best protective properties. The rate of corrosion of such coatings after 7 days of exposure in the NaCl solution was over two times slower than that of coatings containing 2 wt-% of Al2O3 and six times slower than that of a standard nickel coating. Two equivalent circuits: one consisting of two RC circuits and the other one made up of three RC circuits were used for the analysis of the impedance spectra. Regardless of the presence and amount of the Al2O3 particles in the nickel coating, during first day of exposure in the NaCl solution a layer of nickel oxides and hydroxides forms on the surface of the coatings increasing their corrosion resistance. In the case of coatings with 6 wt-% of Al2O3, the passive layer is least vulnerable to the aggressive action of Cl? ions. 相似文献
8.
Zhong-jia Huang 《Surface & coatings technology》2008,202(14):3208-3214
The MoS2 powders were coated with Al2O3 (5 wt.%) through controlling hydrolysis of Al (NO3)3·9H2O. MoS2 powder coated with Al2O3 was written as MoS2/Al2O3 hereinafter. MoS2/Al2O3 powders were put into Ni plating electrolyte bath. Cetyltrimethylammonium bromide (CTAB) — the surfactant was also put into the bath. The experiment proves that MoS2/Al2O3 particles were absorbed onto the Ni plate. The amount of MoS2/Al2O3 deposited on Ni plate rises with the increasing concentration of MoS2/Al2O3 in the bath. The microhardness, micro-surface, phase and the tribological property of the MoS2/Al2O3 multi-plating coating were measured and analyzed. The performances of microhardness and wear resistance of the Ni-MoS2/Al2O3 composite are better than those of Ni-MoS2 composite. 相似文献
9.
The effect of Al2O3 additions to type 316 austenitic stainless steel cold spray coatings was studied. Adding Al2O3 to the feedstock powder increased the overall deposition efficiency, though the Al2O3 itself deposited less efficiently than the stainless steel. Shear testing of the coatings using a shear lug test revealed a change in fracture from cohesive to adhesive with increasing alumina addition. The corrosion behaviour, assessed using anodic polarisation tests of the coatings, showed a shift towards the polarisation behaviour of bulk stainless steel with Al2O3 additions. All of these changes in coating behaviour with Al2O3 additions suggest an improved degree of metallurgical bonding, likely due to increased plasticity in the stainless steel particles. 相似文献
10.
The use of Al-Al2O3 cold spray coatings to improve the surface properties of magnesium alloys 总被引:1,自引:0,他引:1
Pure Al and 6061 aluminium alloy based Al2O3 particle-reinforced composite coatings were produced on AZ91E substrates using cold spray. The strength of the coating/substrate interface in tension was found to be stronger than the coating itself. The coatings have corrosion resistance similar to that of bulk pure aluminium in both salt spray and electrochemical tests. The wear resistance of the coatings is significantly better than that of the AZ91 Mg substrate, but the significant result is that the wear rate of the coatings is several decades lower than that of various bulk Al alloys tested for comparison. The effect of post-spray heat treatment, the volume fraction of Al2O3 within the coating and of the type of Al powder used in the coatings on the corrosion and wear resistance was also discussed. 相似文献
11.
Anna Góral Lidia Lityńska-Dobrzyńska Marcin Kot 《Journal of Materials Engineering and Performance》2017,26(5):2118-2128
Metal matrix composite coatings obtained by electrodeposition are one of the ways of improving the surfaces of materials to enhance their durability and properties required in different applications. This paper presents an analysis of the surface topography, microstructure and properties (residual stresses, microhardness, wear resistance) of Ni/Al2O3 nanocomposite coatings electrodeposited on steel substrates from modified Watt’s-type baths containing various concentrations of Al2O3 nanoparticles and a saccharin additive. The residual stresses measured in the Ni/Al2O3 coatings decreased with an increasing amount of the co-deposited ceramics. It was established that the addition of Al2O3 powder significantly improved the coatings’ microhardness. The wear mechanism changed from adhesive-abrasive to abrasive with a rising amount of Al2O3 particles and coating microhardness. Nanocomposite coatings also exhibited a lower coefficient of friction than that of a pure Ni-electrodeposited coating. The friction was found to depend on the surface roughness, and the smoother surfaces gave lower friction coefficients. 相似文献
12.
Al18B4O33w/Co composite particles were prepared successfully through electroless plating Co on Al18B4O33 whiskers. The growth behavior of the coatings, the effect of the process parameters and the electromagnetic properties of the prepared Al18B4O33w/Co composite particles were investigated. The reduced Co nucleated first on the pre-activated surface of the whiskers to form insular particles which then grew larger gradually and eventually merged together to form continuous coatings. The reaction rate increased but the mass gain decreased with the increase of the bath pH and the bath temperature. The crystallinity of the deposited Co decreased with the increase of phosphorous content as well as the bath temperature. The effect of loading is much weaker compare to that of bath pH and bath temperature. The permittivity and the permeability of the prepared Al18B4O33w/Co composite particles are markedly higher than those of the raw Al18B4O33 whiskers in microwave band. Relaxation resonance is found in the samples with thick Co coatings due to the presence of eddy current, which deteriorates the permeability of the Al18B4O33w/Co composite particles. 相似文献
13.
采用阴极等离子电解沉积弥散Pt颗粒增韧YSZ-Pt/Al2O3-Pt双层复合涂层。涂层中弥散的Pt颗粒阻碍的氧在涂层中的扩散,提高了涂层的抗氧化性能。Pt颗粒的弥散增韧显著提高了涂层的断裂韧性,缓解了陶瓷层与合金基体在高温下产生的热应力,使得涂层在高温服役过程中具有良好的抗剥落性能。 相似文献
14.
Nano-ceramic composite coatings were prepared by the electrodeposition method using sulphamate electrolyte. Nickel was chosen as the metal matrix and nano-Cr2O3 particles were chosen as the reinforcement. The surface morphology and the particle distribution in the coating were analysed using field emission scanning electron microscope (FESEM). The particle content was obtained using energy dispersive X-ray analysis (EDAX). A change in the surface morphology of Ni was seen on the incorporation of Cr2O3 particles. The coatings were characterized for their structure and no change in the diffraction pattern was seen between plain Ni and Ni-Cr2O3 composite. The mechanical property like microhardness and tribological behaviour of the nano-composite coatings was studied and it was observed that the incorporation of Cr2O3 particles enhanced the mechanical properties of Ni matrix. The nano-composites were analysed for their thermal stability and corrosion resistance. An improvement in thermal stability was observed but no change in the corrosion behaviour of Ni was seen on the incorporation of nano chromium oxide particles. 相似文献
15.
Cagri Tekmen Yoshiki Tsunekawa Masahiro Okumiya 《Surface & coatings technology》2008,202(17):4170-4175
In-situ plasma spraying (IPS) is a promising process to fabricate composite coatings with in-situ formed thermodynamically stable phases. In the present study, mechanically alloyed Al-12Si, B2O3 and TiO2 powder was deposited onto an aluminum substrate using atmospheric plasma spraying (APS). It has been observed that, during the coating process, TiB2 and Al2O3 are in-situ formed through the reaction between starting powders and finely dispersed in hypereutectic Al-Si matrix alloy. Also, obtained results demonstrate that in-situ reaction intensity strongly depends on spray conditions. 相似文献
16.
将NiCr-Cr3C2复合粉和Ni包MoS2粉按不同比例混合,制成三种喷涂粉末,采用等离子喷涂技术在304不锈钢表面制备复合自润滑涂层,并对涂层的物相组成、显微组织及摩擦磨损性能进行了研究。结果表明:三种涂层的物相组成相同,主相均为Cr7C3,Ni和MoS2;涂层与基体的结合为机械结合,孔隙率较低,表面有少量微裂纹;喷涂粉末中的Ni包MoS2粉偏少或偏多都会导致涂层的摩擦磨损性能变坏,Ni包MoS2粉质量分数为30%时,涂层的摩擦系数及磨损率最低,分别约为0.36和3.3×10-4mg/s。 相似文献
17.
Qiang Wang Kevin Spencer Nick Birbilis Ming-Xing Zhang 《Surface & coatings technology》2010,205(1):50-4671
Al-Al2O3 composite coatings were produced on AZ91D magnesium alloy substrates using kinetic metallization (KM), which is a special type of cold spray using a convergent barrel nozzle to attain sonic velocity. The effect of the volume fraction of Al2O3 particles and KM spray temperatures on the microstructure, hardness of the composite coatings, the deposition efficiency, and the bond strength between the coating and substrate was studied. Results show that addition of Al2O3 particles not only significantly improves the density of the coating, but also enhances the deposition efficiency to an optimum value. The bond strength of the composite coatings with the substrate was found to be much stronger than the coating itself, measured using a specially designed lug shear method. Furthermore, based on bond strength data and SEM analysis, higher Al2O3 content resulted in a failure mode transition from adhesive failure to cohesive failure. This is considered a result of a competition between the strengthening of the ceramic reinforcing particles at the coating/substrate interface, and the weakening of coating cohesive strength due to an increase in the proportion of weaker Al-Al2O3 bonds compared with stronger Al-Al bonds. Characterisation of the composite coating in terms of hardness, porosity and microstructure was also conducted. 相似文献
18.
19.
Air plasma sprayed TBCs usually include lamellar structure with high interconnected porosities which transfer oxygen from YSZ layer towards bond coat and cause TGO growth and internal oxidation of bond coat.The growth of thermally grown oxide (TGO) at the interface of bond coat and ceramic layer and internal oxidation of bond coat are considered as the main destructive factors in thermal barrier coatings.Oxidation phenomena of two types of plasma sprayed TBC were evaluated: (a) usual YSZ (yttria stabilized zirconia), (b) layer composite of (YSZ/Al2O3) which Al2O3 is as a top coat over YSZ coating. Oxidation tests were carried out on these coatings at 1100°C for 22, 42 and 100h. Microstructure studies by SEM demonstrated the growth of TGO underneath usual YSZ coating is higher than for YSZ/Al2O3 coating. Also cracking was observed in usual YSZ coating at the YSZ/bond coat interface. In addition severe internal oxidation of the bond coat occurred for usual YSZ coating and micro-XRD analysis revealed the formation of the oxides such as NiCr2O4, NiCrO3 and NiCrO4 which are accompanied with rapid volume increase, but internal oxidation of the bond coat for YSZ/Al2O3 coating was lower and the mentioned oxides were not detected. 相似文献
20.
Won-Hee Lee Hyung-Jun Kim Dong-Won Lee Min-Goon Jeong Dae-Soon Lim Song-Min Nam 《Surface & coatings technology》2012,206(22):4679-4684
We attempted the room-temperature fabrication of Al2O3-based nanodiamond (ND) composite coating films on glass substrates by an aerosol deposition (AD) process to improve the anti-scratch and anti-smudge properties of the films. Submicron Al2O3 powder capable of fabricating transparent hard coating films was used as a base material for the starting powders, and ND treated by 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES) was added to the Al2O3 to increase the hydrophobicity and anti-wear properties. The ND powder treated by PFOTES was mixed with the Al2O3 powder by ball milling to ratios of 0.01 wt.%, 0.03 wt.%, and 0.05 wt.% ND. The water contact angle (CA) of the Al2O3-ND composite coating films was increased as the ND ratio increased, and the maximum water CA among all the films was 110°. In contrast to the water CA, the Al2O3-ND composite coating films showed low transmittance values of below 50% at a wavelength of 550 nm due to the strong agglomeration of ND. To prevent the agglomeration of ND, the starting powders were mixed by attrition milling. As a result, Al2O3-ND composite coating films were produced that showed high transmittance values of close to 80%, even though the starting powder included 1.0 wt.% ND. In addition, the Al2O3-ND composite coating films had a high water CA of 109° and superior anti-wear properties compared to those of glass substrates. 相似文献