Dissertation > Excellent graduate degree dissertation topics show

Ni Surface Alloying Prepared on W Substrate and W/Cu TLP Bonding

Author: MengQingBei
Tutor: ShenYiFu
School: Nanjing University of Aeronautics and Astronautics
Course: Materials Processing Engineering
Keywords: Tungsten nickel transient liquid phase bonding double glow plasma metallurgical bonding
CLC: TL627
Type: Master's thesis
Year: 2011
Downloads: 79
Quote: 3
Read: Download Dissertation

Abstract


Controlled thermofusion energy is regarded as the most potential energy in 21th century. One of the key problems of controlled thermofusion energy is the research of―plasma facing components‖. The components require the material equiped with the property of high heat conductivility as well as high thermal resistance. But none of materials could meet the needs; therefore, the joining technique is expected as a proper approach to improve the properties of the conventional materials. Tungsten, which have high melting point, can be used as the armor, while copper and copper alloys, which have high thermal conductivity, can be used as coolant. In the present work, the transient liquid phase (TLP) diffusion bonding of tungsten and copper alloy as well as the surface nickel alloying of tungsten were investigated in details.The nickel alloying of tungsten was investigated preliminarily. It shows that the Ni-modified layer on tungsten consists of Ni deposited layer (19μm in thickness), transition layer (2~3μm in thickness), and tungsten substrate. The mechanism of Ni-modified layer on tungsten was also discussed. It is found that the transient layer and deposited layer formed by the vacancy diffusion and surface absorption of nickel atoms, which is induced by plasma bombardment.Transient liquid phase diffusion bonding of tungsten and copper alloy were successfully carried out in a vacuum furnace by using the interlayers consisted of 62Cu-38Mn-2Ni, 62Cu-38Mn-5Ni and 62Cu-38Mn-8Ni (wt.) powder system. The thickness of interlayer was 100μm, and the surface of tungsten had the Ni-modified layer. The experimental results show that the dense microstructures of the joints as well as the sound bonding coherence with the base materials are obtained using the former two interlayers, and using the 62Cu-38Mn-8Ni as the inter-layers results in the formation of the loose microstructures. The tensile strengths of the three joints are 112.5MPa, 135.4MPa and130.8MPa, respectively. It also shows that with increasing the Ni content from 2wt%to 5wt%, the microstructure becomes denser, while the tensile strength also shows an enhancement. However, when the concentration of Ni increased to 8%, the densification of the joint becomes decreased. It shows that with increasing the bonding temperature and the holding time, a denser and more homogeneous microstructure consisting of less amount of pores are obtained, thereby leading to an increase in the tensile strength. The mechanism of TLP bonding of tungsten and copper was discussed by means of fracture analysis. The bonding mechanism of W to Cu alloy is found to be a combination of TLP bonding and solid diffusion bonding. The TLP acts as a feasible the bonding mechanism of the interlayer and the Cu alloy, as well as the interlayer and the Ni layer; while the solid diffusion bonding mechanism prevails between the Ni layer and the W substrate.

Related Dissertations

  1. Nickel Accumulation and Toxicity to Earthworm Eisenia Fetida in a Range of Chinese Soils,X131.3
  2. Influence of Various PH and the Treating Time on Mechanical Property and Surface Structure of Ni-ti Orthodontic Wire,R783.5
  3. Preparation of tungsten oxide based nanomaterials and gas properties,TB383.1
  4. Construction, Characterization and Properties of Tp~*-Containing W/S/Cu Clusters,O611.4
  5. Preparation and Optical Properties of PS/QDs Nanofibers and Tungsten Oxide Nanofibers,TB383.1
  6. Nuclear related materials mechanical properties and microstructure analysis,TL341
  7. Tungsten carbide seal ring surface waviness precision grinding process research,TG580.6
  8. Research on Separating Molybdenum from Tungsten by Solvent Extraction Using H2O2 as Complex Agent,TF804.2
  9. Performance Research of W-20Cu-0.5Co Composites Fabricated by Spark Plasma Sintering,TF124.5
  10. Nickel microlens array mold core micro electroforming process and surface quality,TH74
  11. Study on the Process of Copper Restores the Salt of Molybdenum,TF841
  12. Study and Preparation of W-Cu Composites Reinforced by Film Coated Carbon Fiber, SiC Fiber and SiC Whisker,TB333
  13. Preparation and field emission properties of the of tungsten micro / nanowire arrays,TB383.1
  14. Spherical porous tungsten powder preparation technology research,TB383.3
  15. Preparation and properties of W - 10Cu composites,TB331
  16. Selective Catalytic Oxidation of Cyclohexanol and Benzyl Alcohol by Tungsten Trioxide,TQ203.2
  17. Tungsten Hexachloride and Its Oxide Aryl Phosphine Ligand Catalyzed DCPD Polymerization Activity and PDCPD/ MMT Nano-composites Research,O631.3
  18. Research on Preparation of Miniature Ceramic Heater,TB657.5
  19. Preparation and Tribological Properties of Tungsten Disulfide （WS2） Film,O313.5
  20. Alloy microstructure and mechanical behavior of fine grain 93W-4.9Ni-2.1Fe,TG146.411
  21. Research on Cutting Properties of Diamond Saw Blades and Falling Dust Design of Cutter,TG717

CLC: > Industrial Technology > Nuclear technology > Controlled thermonuclear reactions ( fusion reaction theory and experimental facilities) > Fusion engineering and technical > Fusion Materials
© 2012 www.DissertationTopic.Net  Mobile