ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.255

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.257

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.260

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.271

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.278

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.279

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.281

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractRecent developments in plasma heat treatment equipment and processing techniques are reviewed. This process, which is now firmly established in the UK, is being used in a wide range of applications. Case histories are presented to illustrate some of the associated advantages and potential drawbacks. Temperature uniformity within the vacuum vessel is identified as the major problem when treating mixed workloads. Advances in the field of plasma carburising have led to improvements in the design of nitriding equipment and in particular to the development of pulse power supplies and additional heating systems. Equipment incorporating these features is claimed to give improved temperature uniformity throughout the workload. Plasma carburising equipment is now available and production facilities are operational in the USA, France, Japan, and the FRG. The current status of plasma carburising is assessed, and the areas which present problems are identified.

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.285

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractIt is widely appreciated that Ni–Al can act effectively as a bond coat for thermal sprayed coatings. The origin of this technologically significant phenomenon is generally considered to lie in an‘pexothermic process’associated with solidification of the molten alloy droplets. This exothermic heat has been variously attributed to compound formation, yielding a high heat of reaction, or to heat of oxidation of aluminium. Experimental tests to date have led to ambiguous conclusions. The present study offers a re-examination of this subject using plasma spraying of Ni–Al, composite and prealloyed, in the presence and absence of oxygen. X-ray and electron microprobe analyses were used to characterise the phase structures of the coatings. Coatings plasma sprayed in air showed significant oxidation products, while those plasma sprayed in a vacuum showed the presence of compounds. The results indicate that for Ni–Al the heat evolved during conventional plasma spraying in air is principally due to partial oxidation of the components, and not to alum inide compound formation, as previously suggested. Mechanical property (tensile bond strength, hardness, and cavitation erosion) tests were performed to verify the microstructural findings.

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.293

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor

摘要:

AbstractThe overaging treatment of a continuous annealing line was simulated in the laboratory. The chemical state of the surface of low carbon steel sheet was determined by using ESCA and SEM. The surfaces of a conventional, low alloyed deep drawing quality (DDQ) steel and a dual phase (DP) steel alloyed with Mn and Si were characterised in simulated and production line conditions. The influence of the surface state of the steels on the formation of surface phosphates was investigated. During overaging in the temperature range 200–400°C in a protective H2+ N2atmosphere iron oxide is reduced to metallic iron. The alloying elements manganese and silicon are oxidised. Silicon especially is markedly enriched on the surface, in the form of pure Si02, due to its high diffusibility. The manganese and silicon oxides form particles on the surface during the overaging treatment. The results indicate that iron oxide is dissolved in the particles. Sodium and calcium are also present in their oxide states on the surfaces of the production line sheets; they originate in the rinsing waters used. Temper rolling reduces the amount of surface oxide particles to about half the prerolling value. It is suggested that this is due to the stripping of particles from the surface and the pressing of particles into the steel matrix. The phosphating experiments show that the steel sheets treated in the simulation furnace and taken from the production line form surface phosphates readily. The phosphate crystals are small, uniform, and cover the entire surface.

ISSN:0267-0844    

DOI:10.1179/sur.1989.5.4.299

出版商:Taylor&Francis    

年代:1989

数据来源: Taylor