Potentialunterstützte Herstellung von Metall‐Keramik‐Verbundschichten

Potential assisted fabrication of metal‐ceramic composite coatings A possibility to produce uniform metal‐ceramic composite coatings with a high content of ceramic particles up to 60 vol.% will be presented in this study. This method includes a combination of electrophoretic deposition and electrolytic deposition by several steps. A yttria‐stabilized zirconia coating (Tosoh TZ‐8Y) was first electrophoretically deposited on a ferritic steel plate and then sintered by 1100 °C to an open porous layer. In the next step nickel was electrodeposited into the pores of the layer. By a final annealing step it was possible to improve the bonding of the composit coating on the substrate by diffusion of the metal components.     

预镀镍对化学镀Ni-P-PTFE复合涂层结构和性能的影响

本文研究了预镀镍过程中不同电流密度和不同沉积时间下形成的预镀镍层对Ni-PPTFE(Poly tetra fluoro ethylene)复合涂层的微观结构和力学性能的影响。首先对304不锈钢基体进行合理的前处理,然后在基体上闪镀一层镍,最后在基体上进行化学镀Ni-P-PTFE复合涂层。通过控制预镀镍过程中的电流密度和沉积时间,利用电子扫描显微镜(SEM)、X射线衍射仪(XRD)、纳米压痕仪、WS-2005涂层自动划痕仪、HSR-2M摩擦磨损试验机对复合涂层的微观结构和力学性能进行了表征。结果表明:不同电流密度和不同沉积时间下形成的预镀镍层对Ni-P-PTFE复合涂层的微观组织、涂层硬度、结合力和摩擦系数都具有较大的影响。当电流密度为3.3A/dm~2,沉积时间为6min时,NiP-PTFE复合涂层的综合性能最佳,复合涂层的表面光滑均匀,其硬度和结合强度分别达到3.874GPa和27.45N,表面摩擦系数为0.145。     

Electrophoretic deposition of HA/MWNTs composite coating for biomaterial applications

A composite coating of hydroxyapatite (HA)/multi-walled carbon nanotubes (MWNTs) has been fabricated by electrophoretic deposition (EPD). The nano powders of HA and MWNTs were dispersed in ethanol with total concentration of 0.005 g/mL and MWNTs 20% and 30% contents (wt). And the pH value of suspension was adjusted in a range from 4 to 5. After stabilization the mixture was ultrasonically treated for 3 h to form a stable suspension. Prior to the electrophoretic deposition, the titanium substrate was hydrothermally treated at 140 in NaOH (10 mol/L) solution for 6 h. A titanium sheet and circinal net of stainless steel were used as a cathode and an anode respectively, and a constant deposition voltage of 30 V was applied for 50-60 s in the EPD process. The thickness of the coatings was controlled from 10 mum to 20 mum. The samples of composite coating were then sintered in a resistance tube furnace in flowing argon at 700 for 2 h. The structure of the as prepared coating was characterized by SEM and XRD, and the bonding force of the coating/substrate was measured by an interfacial shear strength test. It is shown that the bonding strengths between the coating and the titanium substrate is as high as 35 MPa. The cell culture experiments indicate that the prepared composite coating of HA/MWNTs possesses good biocompatibility.     

Metal–ceramic composite layers on stainless steel through the combination of electrophoretic deposition and galvanic processes

The use of metal–ceramic composite layers is of considerable technical interest for many areas of application. The use of electrochemical processes makes it possible to realize coatings on stainless steel which combine the properties of the metals with those of ceramics in an outstanding manner. The process presented here is based on a combination of electrophoretic and electrolytic deposition. At the same time, a very high ceramic ratio is attained in comparison to electrolytic dispersion depositions. It was therefore possible to achieve both nickel–zirconium oxide as well as a copper–zirconium oxide coatings with strong adhesive bonds on stainless steel. A preliminary nickel plating or preliminary copper plating of the stainless steel substrate was first realized. A nanoscale zirconium oxide powder (Tosoh TZ-8Y) from an ethanolic suspension was then applied electrophoretically onto this layer and sintered to an open-porous layer with a porosity of 40–50%. After this, the metal was galvanically infiltrated into the pores. An annealing process was then carried out to improve the layer bonding. Solid-state physical tests reveal that a good material bonding of the composite layer onto the substrate occurred as a result of diffusion processes. Metal–ceramic composite layers can be produced through a combination of electrophoretic and electroplating technology with strongly bond on the substrate by a final heat treatment.     

Microstructures and wear properties of TiN-based cermet coating deposited on 1Cr18Ni9Ti stainless steel by electrospark process

A simple and effective surface treatment technique, electrospark deposition (ESD), has been successfully applied to deposit TiN-based cermet coating on stainless steel substrate. The nitrided coating had an average thickness of about 30 μm and formed metallurgical bonding with the substrate. The microstructure of the coating was mainly composed of TiN phase and ferrite (α-FeCr) phase. Its microhardness reached 889HV. The experimental results demonstrated that the nitrided coating had an excellent sliding wear resistance because the hard TiN phase distributed in the coating increased the resistance to micro-cutting and plowing during the sliding wear test, which effectively improves the surface performance of stainless steel substrate.     

Diffusion bonding of electroless Ni plated WC composite to Cu and AISI 316 stainless steel

In this study, a composite containing WC (Tungsten Carbide) and Ni was produced by two different processing routes. Electroless Ni coated WC powders were consolidated and sintered at 1200 °C. Diffusion bonding couples of WC(Ni)-electrolytic Cu, WC(Ni)-AISI 316 stainless steel and WC(Ni)-WC(Ni) were manufactured by using a preloaded compression system under Ar atmosphere. Diffusion bonding was carried out at varying bonding temperatures; 750 °C for (WC)Ni-Cu diffusion couple and 1200 °C for (WC)Ni-(WC)Ni and (WC)Ni-AISI 316 stainless steel diffusion couples. Standard metallographic techniques, Scanning Electron Microscopy and a shear test were employed to characterize the microstructure of bondline and mechanical properties of each diffusion couple, respectively.     

钛合金表面电泳沉积法制备YSZ/HAp纳米复合涂层

采用电泳沉积法在钛合金基体上制备了YSZ/HAp纳米复合涂层,用场发射扫描电镜、X射线衍射和能量散射谱对复合涂层HAp外层的表面形貌和晶相、复合涂层的断面形貌及元素组成分布进行分析研究,通过粘结-拉伸实验测定了涂层与基体的结合强度.结果表明YSZ/HAp纳米复合涂层与钛合金基体的结合强度明显高于HAp单一涂层与钛合金基体的结合强度,说明YSZ/HAp的复合缓和了HAp涂层与钛合金基体之间的热膨胀系数失配现象,改善了涂层与基体之间的结合.     

Investigation on diffusion bonding of functionally graded WC–Co/Ni composite and stainless steel

A functionally graded WC–Co/Ni composite (FGWC) and 410 stainless steel (410ss) were successfully bonded by diffusion bonding. With the bonding temperature or holding time increasing, the tensile strength of the joints increased firstly and then decreased. The maximum tensile strength of the FGWC/410ss joints was 195 MPa bonded at 950 °C for 80 min. A diffusion layer was formed between the Ni layer and the 410ss as a result of the interdiffusion of Ni and Fe. The Ni layer could release the residual stresses of the FGWC/410ss joints. The fracture of the FGWC/410ss joints occurred in the Ni layer by the way of ductile fracture.     

钛涂覆多孔羟基磷灰石涂层的制备及其生物活性

在纯钛基体表面通过电泳沉积的方法制得壳聚糖/羟基磷灰石(CS/HA)复合涂层, 然后将复合涂层烧结形成多孔HA涂层。采用SEM对多孔HA涂层的形貌进行观察, XRD分析涂层的物相组成, 粘结拉伸实验测定涂层与基体的结合强度, 1.5倍人体模拟体液(1.5SBF)浸泡测定涂层的生物活性。结果表明: 当悬浮液中CS与HA质量比为1∶1时, 制得的CS/HA复合涂层经过700℃烧结处理, 涂层中CS热分解致孔形成多孔HA涂层, 孔径在10~25 μm, 涂层与基体的结合强度可达19.5 MPa; 在1.5SBF中浸泡5天后, 多孔HA涂层表面完全碳磷灰石化, 呈现较好的生物活性。      

Fabrication and interaction mechanism of Ni-encapsulated ZrO2-toughened Al2O3 powders reinforced high manganese steel composites

In order to solve the cast-infiltration difficulty and low interface bonding strength of ZrO₂-toughened Al₂O₃ (ZTA) powders reinforced high manganese steel (HMS) matrix composite, uniform and continuous Ni-encapsulated ZTA powders (ZTA_p@Ni) as reinforced phase are fabricated by electroless deposition assisted with ionic liquid additive. The effects of Ethaline concentration, temperature, ZTA concentration and deposition times on the morphology of ZTA_p@Ni have been investigated. Experimental results show that the thickness of Ni coating is about 7–10 μm, and there is no casting crack or shrink on the composite, so compact bonding between ceramic and matrix is obtained. In addition, the impact abrasive wear resistance testing demonstrates that the performance of ZTA_p@Ni reinforced HMS composite is superior to that of matrix. On the basis of experimental analysis, a schematic illustration of the cast-infiltration process is put forward. It implies that Ni-encapsulated ZTA can be wetted with molten HMS matrix to form a ZTA/Al₂NiO₄-Al₂MnO₄/Fe interface layer through Ni diffusion and reactive wetting. The interdiffusion of Ni and other elements at ZTA interface layer can reinforce the interfacial bonding strength to form an interface layer between metal and hard phases.     

Microstructure and mechanical properties of diffusion bonded SiC/steel joint using W/Ni interlayer

This paper describes the design and examination of W/Ni double interlayer to produce a joint between SiC and ferritic stainless steel. Diffusion bonding was performed by a two steps solid state diffusion bonding process. Microstructural examination and mechanical properties evaluation of the joints show that bonding of SiC to steel was successful. EDS and XRD analysis revealed that W₅Si₃ and WC were formed at SiC/W interface. The diffusion products at W/Ni interface, Ni-rich solid solution Ni(W) or intermetallic compound Ni₄W, was found to be dependent on the second step joining temperature. Neither intermediate phases nor reaction products was observed at Ni/steel interface for the joints bonded at the temperature studied. The average tensile strength of 55 MPa which is insensitive to the second step process was measured for as-bonded SiC/steel joint and the failure occurred at SiC/W interface. The hardness near the various bonded interfaces was also evaluated.     

Effect of Cr and Ni on diffusion bonding of Fe3Al with steel

Microstructure at the diffusion bonding interface between Fe₃Al and steel including Q235 low carbon steel and Cr18-Ni8 stainless steel was analysed and compared by means of scanning electron microscopy and transmission electron microscopy. The effect of Cr and Ni on microstructure at the Fe₃Al/steel diffusion bonding interface was discussed. The experimental results indicate that it is favourable for the diffusion of Cr and Ni at the interface to accelerate combination of Fe₃Al and steel during bonding. Therefore, the width of Fe₃Al/Cr18-Ni8 interface transition zone is more than that of Fe₃Al/Q235. And Fe₃Al dislocation couples with different distances, even dislocation net occurs at the Fe₃Al/Cr18-Ni8 interface because of the dispersive distribution of Cr and Ni in Fe₃Al phase.     

真空等离子喷涂碳化硼涂层制备与抗激光辐照性能研究

采用真空等离子喷涂技术,在不锈钢基体上制备碳化硼(B₄C)涂层,并对涂层的组成、结构、沉积效率、结合强度以及抗激光辐照性能进行了表征.结果显示,真空等离子喷涂B₄C涂层中没有出现明显的B₂O₃相,表明真空等离子喷涂可有效避免B₄C氧化现象.采用较细的粉末制备的B₄C涂层较为致密.较高的喷涂功率和较大的氢气流量,有助于改善粉末的熔化程度,从而提高涂层的沉积效率和结合强度.在适宜的工艺参数下,涂层的沉积效率与结合强度可分别达72%与49MPa.激光辐照试验表明,在不锈钢表面沉积B₄C涂层,可以明显改善其抗激光辐照性能.     

Microstructure and Mechanical Properties of Fe-based Amorphous Composite Coatings Reinforced by Stainless Steel Powders

In this study,a few Fe-based amorphous matrix composite coatings reinforced with various portions(4,8 and16 vol.%) of 31 6L stainless steel powders have been successfully produced through high velocity oxy-fuel(HVOF) spraying.The microstructure of the composite coatings was systematically characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM) and transmission electron microscopy(TEM).The main structure of composite coatings remained amorphous while 31 6L stainless steel splats were distributed homogeneously in the amorphous matrix and well connected with surrounding amorphous phase.Bonding strength of coatings to the substrate was determined by "pull-off" tensile tests.The results revealed that the31 6L stainless steel phase effectively improved the bonding strength of amorphous coatings,which is mainly contributed by the strong metallurgical bonding between stainless steel and amorphous splats.The addition of31 6L stainless steel also enhanced the ductility and fracture resistance of the coatings due to the ductile stainless steel phases,which can arrest crack propagation and increase energy dissipation.     

Partial transient liquid phase diffusion bonding of Zircaloy-4 to stabilized austenitic stainless steel 321

An innovative method was applied for bonding Zircaloy-4 to stabilized austenitic stainless steel 321 using an active titanium interlayer. Specimens were joined by a partial transient liquid phase diffusion bonding method in a vacuum furnace at different temperatures under 1 MPa dynamic pressure of contact. The influence of different bonding temperatures on the microstructure, microindentation hardness, joint strength and interlayer thickness has been studied. The diffusion of Fe, Cr, Ni and Zr has been investigated by scanning electron microscopy and energy dispersive spectroscopy elemental analyses. Results showed that control of the heating and cooling rate and 20 min soaking at 1223 K produces a perfect joint. However, solid-state diffusion of the melting point depressant elements into the joint metal causes the solid/liquid interface to advance until the joint is solidified. The tensile strength of all the bonded specimens was found around 480–670 MPa. Energy dispersive spectroscopy studies indicated that the melting occurred along the interface of the bonded specimens as a result of the transfer of atoms between the interlayer and the matrix during bonding. This technique provides a reliable method of bonding zirconium alloy to stainless steel.     

Electrophoretic deposition of zirconia layers for thermal barrier coatings

This paper presents an exploratory investigation of a production route for thermal barrier coatings (TBCs) from a stable zirconia nanopowder suspension by means of electrophoretic deposition (EPD) on a low carbon steel substrate, followed by a consolidation by hybrid microwave sintering.Since the thickness of the green deposit is restricted to a critical thickness, which depends on the curvature of the substrate, a method of repeated deposition and sintering was applied in order to produce thick coatings. The low electric conductivity of the sintered ceramic coating does not inhibit the deposition of additional layers. This method enabled the production of porous coatings with a sintered thickness of 150–300 μm.A finite element model was applied to evaluate the thermal conductivity of the coatings. Values of the order of 0.8 W/mK were obtained which is comparable to that of coatings deposited by other techniques. Hence, the multiple deposited coatings with their thick and porous microstructure have a high potential for thermal barrier coating (TBC) applications.     

用镍基薄带钎料真空熔结Cr3C2-NiCr涂层的组织和性能

提出了一种采用薄带钎料进行真空熔结的新方法，用BNi-2薄带钎料粘贴在Cr3C2-NiCr预置层表面进行了真空熔结处理，对涂层的组织和微动磨损性能进行了研究。结果表明，真空熔结涂层组织致密，涂层与基体、涂层内部硬质相与粘结相之间可形成良好的冶金结合。涂层主要由Cr3C2，Cr7C3，Cr23C6，Ni的硼化物、Cr的硼化物等硬质相和镍基固溶体韧性相组成。基于致密的组织、良好的结合和硬质相强化，真空熔结Cr3C2-NiCr涂层的抗微动磨损性能明显优于等离子喷涂Cr3C2-NiCr涂层和1Crl8Ni9Ti不锈钢。     

Synthesis and characterisation of nanostructured hardystonite coating on stainless steel for biomedical application

Here, nanostructured hardystonite bioceramic (Ca₂ ZnSi₂ O₇) was synthesised from tetraethyl orthosilicate, zinc nitrate hexahydrate, and calcium nitrate tetrahydrate via sol–gel method, dried at 60–120°C, and finally calcinated at 1300°C. X‐ray diffraction (XRD) analysis confirmed the formation of hardystonite bioceramic. Afterwards, electrophoretic method was utilised to coat the hardystonite ceramic on 316L stainless steel (SS). Methanol solution was used as suspension solvent. The best deposition procedure was carried out by electrophoretic device in the voltage of 50 V for 5 min. XRD analysis was employed for phase characterisation and scanning electron microscopy was utilised for microstructural and morphological characterisations of the coatings. Chemical composition of the coating was evaluated by energy‐dispersive X‐ray spectroscopy. The hardystonite coating improved the corrosion resistance of the substrate, so the corrosion current density in the coated samples was less than the uncoated ones (nine times). In order to assess the bioactivity of the coating, simulated body fluid was used. The main results of the coated sample bioactivity demonstrated that the nanostructured hardystonite coating could amend the in vitro SS bioactivity. Therefore, SS coated with nanostructured hardystonite may be a promising candidate to be applied as bioactive hard tissue implants.Inspec keywords: bioceramics, stainless steel, X‐ray diffraction, corrosion protective coatings, X‐ray chemical analysis, sol‐gel processing, calcium compounds, current density, nanofabrication, zinc compounds, scanning electron microscopy, corrosion resistance, calcination, crystal microstructure, nanostructured materials, prosthetics, nanomedicine, electrophoretic coatings, electrophoretic coating techniquesOther keywords: X‐ray diffraction analysis, electrophoretic method, XRD analysis, phase characterisation, microstructural characterisations, morphological characterisations, energy‐dispersive X‐ray spectroscopy, coated sample bioactivity, nanostructured hardystonite coating, zinc nitrate hexahydrate, sol–gel method, 316L stainless steel, tetraethyl orthosilicate, calcium nitrate tetrahydrate, suspension solvent, deposition procedure, scanning electron microscopy, chemical composition, corrosion resistance, corrosion current density, bioactive hard tissue implants, temperature 1300.0 degC, voltage 50.0 V, time 5.0 min, temperature 60 degC to 120 degC, Ca₂ ZnSi₂ O₇      

Zinc-graphite composite coating for anti-fouling application

In this paper, an anti-fouling composite coating was fabricated by blending zinc-graphite alloy powders with epoxy-silicone resin and characterized by EDS, SEM, XRD and ion titration. Compared with stainless steel and epoxy-silicone resin coating, the composite coating significantly inhibited the deposition of CaCO₃ fouling. Only a small amount of fouling was observed on the surface of composite coating after it was immersed in CaCl₂/NaHCO₃ solution. The galvanic corrosion of zinc-graphite powders could release Zn²⁺ ions, which can reduce partially the nucleation and crystal growth rate of CaCO₃ on the surface of composite coating. It was found that the morphologies of CaCO₃ fouling changed from calcite to aragonite as the existence of composite coating. Meanwhile, CaCO₃ fouling was prone to precipitate in bulk solution rather than on the surface of composite coating.     

An experimental study on synthesizing TiC-TiB2-Ni composite coating using electro-thermal explosion ultra-high speed spraying method

The synthesis of TiC-TiB₂-Ni composite coating on steel substrate using electro-thermal explosion ultra-high speed spraying (EEUSS) method has been investigated. The coating exhibits a compact microstructure and good interface bonding. TiC-TiB₂-Ni coating consists of TiC, TiB₂, Ni, as well as the residual C. Microstructure characterization reveals micro-sized clubbed TiB₂ particles with the length of 5-10 µm and submicron-sized spherical TiC particles with the average diameter of 1 µm and these different morphologies are due to their respective crystal structure. The average hardness value for TiC-10TiB₂-Ni and TiC-20TiB₂-Ni are HV0.3 1800 and HV0.3 2000.