摘要:

The devolved, bottom-up, style of management organization of COST is described together with the close-knit, integrated type of research and development that is conducted in the materials programmes by international groups of collaborators representing industry, research institutes and universities. The closely targeted research programme of COST 501, Advanced Materials for Power Engineering, is described in greater detail to illustrate the approach that is followed. Examples of industrial developments are given.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689649

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Creep crack growth tests have been made on Jethete M152 at 550°C under initially mixed-mode (i.e. KI/KII≈1.6) and mode-II crack tip conditions using compact mixed-mode (CMM) specimens. The results of these tests have been compared with mode-I data obtained from compact tension (CT) tests, using aC* approach. The correlation between the mode-I, mode-II and mixed-mode data is reasonably good. However, the scatter band is greater than that obtained from the mode-I results only. The results indicate that theC* approach, which has been used successfully in mode-I situations, may also be useful for predicting creep crack growth in more general situations.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689650

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The thermal and environmental stabilities of boron nitride (BN), aluminium nitride (AIN), and silicon nitride (Si3N4) ceramics have been evaluated using thermochemical modelling. The volatility diagrams of these materials have been established at 2000 K. Master volatility diagrams with equilibrium pressure of dominant vapour species at 1400, 1600, 1800 and 2000 K have also been constructed. The phase stability diagrams of BN and Si3N4have been established to indicate the stability of various oxide and oxynitride phases in equilibrium with these nitrides at different oxygen and nitrogen pressures. These data show that in order to prevent dissociation and volatilization, nitrogen overpressures are required during processing and/or operation at higher temperatures. Vaporization rate data indicate that under congruently vaporizing conditions, the mass losses of silicon nitride are greatest, followed by those of aluminium nitride and then boron nitride.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689651

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

Renewed interest in direct coal-fired gas turbines has led to a close examination of the potentially corrosive effects of coal combustion products on turbine blade materials. Short-term tests using a subscale turbine combustor were run with coal-water fuels (CWF) having coal ash levels around 1%. Deposits formed at gas temperatures of 1100°C (2000°F) on the CoCrAIY-coated specimens cooled to a turbine vane surface temperature of 980°C (1800°F). The deposit-coated specimens were subsequently exposed for 1484 h in a furnace-simulated turbine atmosphere at 980°C (1800°F). Examination of the test specimens showed that two atypical forms of corrosion occurred during exposure to combustor products. Accelerated oxidation was observed after the furnace tests. Additional work is recommended to more fully explore the effects of alternative coal feedstock and degree of coal cleaning on corrosion for this application.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689652

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The effects of pre-oxidation of Incoloy 800H and Inconel 738 as a possible protective measure in reducing erosion-corrosion of the underlying alloy at temperatures up to 700°C have been investigated under conditions of moderate particle velocities and high particle loadings. This research also included assessment of the variation of erosion-corrosion with impact angle and alloy hot hardness. The results showed that the pre-formed scale exerted negligible effect on the erosion-corrosion of the substrate under these conditions. There were no significant differences between the wastage rates of the pre-oxidized and the as received alloys as the temperature was increased. The variation of erosion rate with impact angle followed the classical ductile mode at high temperatures. The reasons why pre- oxidation is ineffective under these conditions are discussed in terms of existing knowledge of erosion-corrosion in similar conditions.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689653

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

High alloyed duplex stainless steels, referred to as super duplex, are being used increasingly for applications in corrosive environments. The higher Cr and Mo contents of these materials can lead to susceptibility toσ-phase precipitation, even during short time exposures to high temperatures. The 800°C aging of a high alloyed duplex stainless steel was investigated. Optical microscopy with image analysis, X-ray diffraction, and SEM were used to determine theσ-phase and to estimate the amount. Mechanical properties such as tensile strength, impact strength and hardness were investigated. It was found that the impact strength is most sensitive to aging at 800°C. Theσ-phase transformation is discussed and the microstructural aspects are described.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689654

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

摘要:

The effect of exposure of Inconel alloy X-750 to air at 1150°C on creep at 700°C and 400 MPa has been investigated. Contrary to the findings for exposure at 1050°C, exposure to air at 1150°C does not impair creep ductility. This is attributable to oxygen diffusion into the alloy at 1150°C being impeded. Evidence is given here to show that during exposure to air at 1150°C diffusion of chromium is fast enough to reach the surface and form a chromium oxide scale, which acts as a barrier to further oxygen diffusion.

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689655

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689656

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor

ISSN:0960-3409    

DOI:10.1080/09603409.1991.11689657

出版商:Taylor&Francis    

年代:1991

数据来源: Taylor