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Tungsten and tungsten alloys with a high melting point, high density, high strength, low coefficient of thermal expansion, excellent performance, with the defense industry and the rapid development of the national economy, tungsten and tungsten alloy thin-walled or complex shape parts sector applications increasingly widespread, its performance and cost-effective requirements are also increasing. However, rapid economic growth also makes tungsten resource consumption growing, resulting in a shortage of resources and increased prices. In addition, the traditional forming methods such as chemical vapor deposition, physical vapor deposition, self-propagating high-temperature synthesis in the preparation of tungsten and tungsten alloy thin-walled or complex shape parts, powder metallurgy and other obvious limitations. Plasma spray forming technology because of its high temperature, high-speed, high efficiency, low cost, easy to operate and shaped pieces easy to control the thickness and other technical characteristics provide an ideal way for tungsten and tungsten alloy parts near net shape. In this paper, plasma spraying near net shape precision tungsten nozzle, tungsten crucible, small tungsten and tungsten-rhenium alloy heating element, tungsten shaped charge liner, tungsten throat and 95W-3.5Ni-1.5Fe thin-walled rotating body parts, study subsequent processing of high-temperature sintering, hot isostatic pressing, swaging forming parts microscopic morphology, grain size, relative density, micro-hardness, tensile strength, compression strength and yield strength of the law, and in-depth analysis of the densification mechanism of class processing technology. This paper, the main research contents and conclusions are as follows: system research such as plasma spraying process parameters on the microscopic structure of the tungsten deposition layer, an optimized such as plasma spray forming process parameters as: spraying power 40kW, spraying distance 150mm, hydrogen flow 50L / h. After testing, plasma spray forming all kinds of tungsten shaped member opening rate, relative density, micro-hardness, tensile strength and compressive strength of approximately 7.5% .88.5% .341.7 HV0.025, 55.1MPa and 581.3MPa. Such as plasma spray forming process, be strictly controlled to prevent the forming parts because of increased wall thickness possible forms of cracking failure, effective measures can be taken to optimize the spraying process, batch spray and protective atmosphere. -Depth study of the plasma spray forming tungsten shaped pieces of hot isostatic pressing densification behavior and mechanisms. The study found that with the hot isostatic pressure rise time and deal with micro-cracks and pores in the sediments gradually healing, gradually increase the mechanical properties of the formed parts, by the two-step hot isostatic pressing, forming pieces of density, micro hardness, tensile strength and compressive strength were increased to 96.7%, 547.8HV0.025, 245.3MPa and 1443.5MPa. In this paper, a heating, recrystallization, lamellar rearrangement, elastic contact, plastic flow, diffusion creep consists of six stages of the hot isostatic densification mechanism. 3 in-depth analysis of the plasma spray forming W / Re alloy Re effects. The study found that the trace Re solid solution strengthening effect of the element can be effectively suppressed W grains grown up in a high temperature environment, but also change the deformation mechanism of the material in the cold working process, different from the the pure W member of brittle fracture, W / Re alloy at room temperature compression process yield. In addition, plasma spray forming the mechanical properties of the W / Re alloy increases with the sintering of the extension of time. By 2300 ° C for sintering after 6h, W / Re alloy microstructure, hardness, tensile strength, compressive strength and yield strength, respectively 490.8HV0.025, 384.5MPa, 1922.5MPa, 947.4MPa, under the same sintering conditions was significantly higher than that of pure W The mechanical properties of the member. High-temperature sintering and swaging processing technology roadmap densification of spray forming parts. The results showed that the 2300 ° C high temperature sintering allows the deposited layer by layer sheet structure transformed into a granular structure, and its relative density, micro-hardness and the tensile strength was increased to 97.9%, by 381.5HV0.025 228.5MPa. After two swaging processing tungsten / molybdenum rod total compression rate of 21% the deposition layer density is further increased to 98.5%, the microhardness increased significantly to 620.4HV0.025. However, the deposited layer by surface inwardly tungsten particles degree of deformation by swaging processing gradually weakened, deformation of the entire sample showed a greater unevenness. In addition, the deposition layer is sintered at high temperature for the polyhedron tungsten grain and pore complex sedimentary grains in a small amount of porosity can not be eliminated, swaging processing still can not reach full density. 5 plasma spray forming tungsten the throat insert the ground ignition test experiments. Tungsten throat insert thermal shock ablation performance the linear ablation only 0.08mm/20sec, the targets are exceeded the performance of the same size conventional graphite throat. Studies have shown that tungsten throat insert various parts of the ablation morphology and ablation mechanism significantly different the convergence segment by mechanical erosion, thermochemical ablation supplement; throat mechanical erosion, melting ablative and thermal ablation three mechanisms co-exist, its ablative most serious; diffusion segment compared with thermochemical ablation, ablation of the lowest level. 6. Prepared by high energy ball milling, spray drying granulation and induction sintering process route 95W-3.5Ni-1.5Fe composite coating powder using plasma spraying near net shape technology to prepare high-density alloy thin-walled rotary vacuum solid phase sintering and vacuum liquid phase sintering on microstructure and mechanical properties of. The density of plasma spray forming high density alloy is 87.70%, microhardness 388.0HVo.025, the tensile strength was 102.6MPa, the elongation is close to zero. 1200,1300 ° C sintered after the formation of a liquid phase, forming member remains the original lamellar structure definitions; 1400 ° C sintering produces only a small amount of liquid, it is difficult to carry out effective particle rearrangement remains lamellar structure of the deposited layer, forming pc fracture to intergranular fracture; sintering at 1465 ° C due to the generation of a large number of liquid phase, particle rearrangement occurs rapidly deposited layer by the original lamellar structure into spherical tungsten particles and mesh Y consisting of two-phase alloys organization, density, micro-hardness, tensile strength and elongation were increased to 98.05%, of 493.5HVo.025, 567.1MPa and 5.7%, showing fracture to intergranular fracture and transgranular fracture, supplemented by the fracture mode; When the temperature rises further, to 1485 and 1500 ° C, the tungsten particles grow significantly, gamma phase increased evaporation, forming pieces of fracture are denominated intergranular fracture, but some micro-hardness, tensile strength and elongation properties reduced. Proposed and demonstrated an early solid-phase sintering and recrystallization phase, liquid phase formation and penetration stage, dissolution - precipitation stage Ⅰ, particle rearrangement stage of dissolution - precipitation II solid skeleton formation and grain growth stage five stages of the plasma spray forming high-density alloy densification mechanism.
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