Advanced Materials Research Vols. 189-193

Abstract: This article uses independently develops micro-oxidation installment, systematically studied and optimized the silicate system solution,the silicate and the different recombiner composition compound system solution that are used in SJDM-1 rare earth magnesium alloys micro-oxidation and different electrical parameters that affect corrosion resistance of ceramic coating through the condition experiment and the orthogonal experiment.Using scanning electron microscopy (SEM) , X-ray diffraction (XRD) , coat thickness tester and drip experiment, the surface morphology of ceramic layer of SJDM-1 rare earth magnesium alloys are observed,and composition, thickness and corrosion resistance of SJDM-1 rare earth magnesium alloys in different solution are tested. Meanwhile combining the micro-oxidation solution and electrical parameters that are optimized, the difference of corrosion resistance between the hydration seals hole and solvent seals hole are compared after micro-oxidation. In addition, corrosion resistance of MAO ceramic layers between the two different materials RE magnesium alloys (casting SJDM-1, deformation SJDM-2)under the same conditions. Finally, micro-oxidation solution failure and the process of the ceramic layer corrosion are analysed. Mechanism of the discharge breakdown that influence the corrosion resistance of the micro-oxidation ceramic coating is explored, come to the internal and external factors that affect corrosion resistance of the micro-oxidation ceramic layer.

Abstract: A new hot dip Zn-5%Al-0.3%Mg alloy coating was performed on cold rolled common steel. The hot-dip process was executed by self-made hot dip galvanising simulator (China patent, No.201010160353). The corrosion resistance of alloy-coated steels was detected by neutral salt spray test . SEM and EDS test results demonstrate that Mg is mainly distributed in the crystal boundary. XRD test results shows corrosion product of Zn-5%Al-0.3%Mg alloy coating is mainly Zn₅(OH)₈Cl₂•H₂O. The characteristic of Zn₅ (OH)₈Cl₂•H₂O is dense and insoluble, so it is protective. In order to study the anticorrosion mechanism, all the tests of the Zn-5%Al-0.3%Mg alloy were carried out with Zn-5%Al coating together.

Abstract: The friction and wear properties of AISI 52100 steel and DLC coatings were evaluated while being lubricated with silicone oil, PAO and PAG lubricants by using a reciprocating ball-on-disk sliding UMT tester. The morphologies of original surface and worn surfaces for the DLC and Ti doped DLC coatings were observed by using a scanning electron microscope. The results show that the DLC coatings have better tribological properties than AISI 52100 steel under silicone oil, PAO and PAG lubrication conditions. In addition, the DLC coatings have much better wear resistance than the AISI 52100 steel.

Abstract: Plasma spraying process was carried out to prepare Al₂O₃+13%TiO₂ ceramic coating on AZ9_{Subscript text}1D magnesium alloy by an orthogonal experiment. The microstructural characteristics and properties of coating were investigated. The results reveal that the bonding strength of optimized Al₂O₃+13%TiO₂ coating reach 19.54MPa. The thermal shock failure of the coating is mainly due to fatigue under thermal cycling stress. The corrosion resistance of magnesium alloy is remarkably improved by plasma-sprayed Al₂O₃+13%TiO₂ coating.

Abstract: Micro-arc oxidation (MAO), also called plasma electrolytic oxidation (PEO), anodic spark deposition (ASD), or micro-arc discharge oxidizing (MDO), is an effective surface treatment technique which come from anodic oxidation technology. Via increasing the anodic voltage breaking through faraday area to a high stage accompanied by micro-arc discharge phenomenon, It indicated the ceramic coatings thickness increase along with the scanning times increase, while the thickness increment reduces. The phase composition, morphology and element distribution was studied by X-ray diffraction, scanning electron microscopy and line scanning. The morphology of the ceramic coatings shows it divided into compact layer and loose layer. And it composes of α-Al₂O₃ and γ-Al₂O₃.

Abstract: In this paper, the method of electroless nickel-plating on carbon fiber surface is introduced, and surface metallization of carbon fiber is researched. The study includes pretreatments before plating, design of the plating solution composition, microscopic analysis of coating materials, and bonding strength testing between the coating and the substrate. The study show that pretreatments on carbon fiber surface have an important impact on metallization. In pretreatments, coarsening treatment changes the surface state of carbon fiber, increases surface area; while dispersing eliminates the reunion phenomenon of the fiber. Plating solution composition is the key factor of nickel-plating on carbon fiber surface, the best components of solution are 30g/L nickel sulfate, 20g/L lactic acid, 30g/L sodium hypophosphite. The surface metallization of carbon fiber is realized by chemical nickel plating, and the coating combined well with fiber, uniformity, complete and bright. The coating gained in the experiment is Ni-P amorphous alloy.

Abstract: The electron beam welder is the application example of high-energy beam on the Welding equipment. In order to achieve a variety of logic control device, the traditional control system of the electron beam welder is based on PLC. It exist a lot of the disadvantages in the traditional control system of the electron beam welder. Especially, its welding energy has the simplex form of supply and the asynchronous with trajectory. In order to deal with this problem, it is developed the CNC system with the form of industrial personal computer (IPC) + motion control card in this paper. This CNC system can achieve the unified programming and synchronous control of the trajectory and two-energy magnitude: the focusing current and electron beam current. This CNC system can make up for the deficiency of the traditional control system and improve the efficiency and precision of weld. Feedback from its application on the electron beam welder indicates that it works reliably and the performance is satisfactory.

Abstract: The microstructure and properties of plasma sprayed Al₂O₃-13wt%TiO₂ (AT13) coating on AZ91D magnesium substrate were investigated. The results indicated that the AT13 coatings consisted of γ-Al₂O₃, α-Al₂O₃ and Al₂TiO₅, presented a lamellar structure with pores and microcracks. The microhardness increased from the substrate to the coating, significantly conformed to Normal and Weibull distributions. The friction coefficient of AT13 coating increases with the increase of time, load and rotation speed under lower working condition (10N, 20N;100r/min,150r/min), but abnormal phenomenon appeared under high load and rotational speed.

Abstract: Ti and TiN were deposited on mold steel 3Cr2W8V by PVD, then processed with the technology of electron beam surface alloying. The microstructure of modified and the influence of modified layer on wear performance of 3Cr2W8V were studied. The result shows that the section hardness of coating Ti material has increased by 35% at most when the times of treatment reach 25, the distribution of the section hardness is waved, the pick point of section hardness is at depth of 100μm to 200μm, The friction of coating Ti layer is decrease by 50% at most when the times of treatment reach 20, and the abrasion loss is totality descend by about 80%;the section hardness of coating TiN material has increased by 35% at most also when the times of treatment reach 25, the pick point of section hardness is at depth of 150μm to 250μm, the friction factor of material is waving with descend while the times of bombardment increased; the abrasion loss is totality descend by about 90%.

Abstract: Metallic hollow sphere structure cellular material is a type of super-light cellular metallic material. Its basic cell is thin-walled metallic hollow sphere. A series of quasi-static uniaxial compression experiments of two spheres array, three spheres array and tetrahedral packing structure were conducted. It is found that one sphere produces deformation at the contact place of two spheres, and the deformation is larger than that at the contact place of plates. The three spheres array and tetrahedral packing structure have the same phenomenon. Then, the Young’s moduli of these three models had been studied, and it is found that the tetrahedral packing structure has a larger value than the others. The compressive deformation behaviors of two and three spheres with the spheres glued together were studied too. These research findings can be the basis of the design of MHS structure cellular material.