Papers by Keyword: Metallurgical Bonding

Abstract: The metal powder-plate composite rolling, which combines the Monel 400 metal powder and 45^# steel plate, is a novel method to prepare composite strips. By using a new high-rigidity two-high metallurgical powder 350mm test mill designed and developed independently, the composite sheet is achieved by the process of “cold rolling+sintering+hot rolling”. Then the cross-section of the rolled composite sheet is analyzed. The results show that 0.9mm Monel 400 powder and 4.3mm 45^# steel plate can be successfully rolled into a 4.4mm composite sheet after 4 passes of cold rolling, sintering at 1200°C and hot rolling at 900°C with furnace cooling. The detection analysis shows that transition layer of the composite sheet has obvious element diffusion without interface. The bonding surface has changed from physical bonding to metallurgical bonding, and the combination is excellent.

Abstract: AA4045/AA3003 cladding billets with different clad ratios were fabricated by direct chill casting process. The macrostructures, microstructures, compositions distribution and the mechanical properties near the bonding interface were investigated in detail. The results show that the cladding billet with few defects could be obtained by semi-continuous casting process. The metallurgical bonding was formed due to the diffusions of elements. The decreasing of clad ratio changed the microstructure at the interface and reduced the thickness of diffusion layer. The hardness around the interface is higher than that of AA3003 side but lower than that of the other side, indicating that the interface yield strength is also higher than that of AA3003. After extrusion process, the characteristics of the interface remain that of as-cast cladding billet.

Abstract: The AA4045/AA3003 cladding billet, which has a low clad ratio of 7.5% in size of φ160mm/φ148mm, was prepared successfully by the modified direct chill casting process. Microstructures, elements distribution and mechanical properties of the bonding interface were examined. The results show that metallurgical bonding interface can be obtained with the optimal parameters. The metallurgical bonding interface is free of any discontinuities due to the elements diffusion across the interface. The hardness of the interfacial region is higher than that of the AA3003 but lower than that of AA4045, suggesting that the interface bonding strength is higher than the strength of AA3003. The shearing strength is 82.3 MPa, indicating excellent metallurgical bonding.

Abstract: With the cladding casting equipment, which was self-designed and self-made, 4045/3003 composite ingot, which is in size of Φ140mm/Φ110mm, has been manufactured by direct cooling continuous casting by adjusting and optimizing the technological parameters. The process was investigated involving macro-morphology and microstructure near the interface between the two different aluminum alloys at different positions, and distributions of both components and hardness of the cladding ingot. In addition, the tensile strengths were tested. The results showed that metallurgical bonding of two different aluminum alloys could be obtained by direct-chill semi-continuous casting process. The diffusion layer, which is about 15μm on average, has formed on the two sides of composite interface during casting process. From the side of 4045 aluminum alloy to the side of 3003 aluminum alloy, the Si content has a trend to decrease, as well as the hardness, while the Mn content has a trend to increase gradually. Tensile strength of the coated ingot reaches 117.3MPa, which is higher than the core-material matrix (3003 aluminum alloy), indicating the bonding of the two alloys belongs to metallurgical bonding.

Abstract: Cathodic plasma electrolysis (CPE) is an emerging surface engineering technology in the recent years. In present work CPE was successfully used for deposition Ni-P coatings on carbon steel. The deposition experimental results show that CPE possesses high coating deposition rate, faster than 4 μm/min. SEM observations unveil the bonding between Ni-P coating and substrate is metallurgical. XRD diagram analysis indicates that the phases of as-deposited Ni-P coating are Ni and Ni3P, transformed from amorphous to crystallized state. The corrosion resistances of CPE and electroless plating (EP) coating have also been discussed by polarization curves in 3.5% NaCl solution at room temperature. Scratch tester was applied to study film-substrate adhesion of CPE Ni-P coating comparing with EP Ni-P coating.

Abstract: Copper has some excellent performances in anti-erosion and high thermal conductivity. It is applicable in many important fields. In the paper, two methods of preparing Ni-Cr alloy cladding layer on the surface of copper are proposed, including the spray welding and YAG pulse laser cladding .Then the Ni-Cr alloy layer prepared on the copper is investigated by optical microscopy, there is no hole and crack in the cladding layer. The experimental results show the coating is metallurgically bonded with the substrate. In comparison to the prepared cladding layers, the Ni-Cr cladding layer prepared by YAG pulse laser is the better, the size of copper is not restricted, and the copper substrate isn’t preheated.

Abstract: In order to produce new generation monolayer brazing CBN(cubic boron nitride) grinding wheels, an active filler alloys(Ag-Cu-Ti) were tested in vacuum furnace. The results show that Ag-Cu-Ti alloy exhibits good wetting and bonding toward as CBN grits. SEMEDS microanalyses have shown that during brazing Ti in Ag-Cu-Ti alloy segregated preferentially to the surface of the CBN to form a Ti-rich reaction produce. X-ray diffraction reveals that the wetting and bonding behaviour on CBN surface by Ag-Cu-Ti alloy melt is realized through TiN and TiB2 which is produced by interaction between Ti atoms of Ag-Cu-Ti alloy and N or B atoms of CBN surface.

Abstract: Laser additive direct deposition of metals is a new rapid manufacturing technology, which combines with computer aided design, laser cladding and rapid prototyping. The advanced technology can build fully-dense metal components directly from the information transferred from a computer file by depositing metal powders layer by layer with neither mould nor tool. Based on the theory of this technology, an experimental setup for laser rapid manufacturing process was developed. Through this state-of-the-art automated apparatus, some cladding experiments were performed to grasp the process features of laser rapid manufacturing technology. Finally, the columnar/equiaxed grain growth transition model is used to explain the morphology characteristic. Accordingly, the appropriate microstructure can be obtained by adjusting the processing parameters.

Abstract: Based on analysis of the mechanism of Electrical Discharge Machining (EDM) and the characteristics of deposition processing, the processing conditions of micro EDM Deposition (micro EDD) are determined. Micro EDD is a new EDM method taking air as machining medium, using narrow pulse width, long pulse interval, low discharge current and connecting the tool electrode with the anode of pulse generator. Using EDM shaping machine and brass, tungsten and steel as tool electrode respectively, micro cylinders are deposited on high-speed steel surface. And then the microstructure of deposit is analyzed detailedly. Results show that elements of the deposited material distribute uniformly, whose components depend on the tool electrode material. As the high cooling rate of the solidification process, the deposit grain size refines obviously, which leads to the hardness of tungsten or steel deposit increasing. Moreover, the Metallurgical bonding has occurred on the interface between deposit and high-speed steel base, whose thickness is about 5μm.