Papers by Author: Psantu K. Datta

Abstract: A nickel aluminide coating was formed on P92 steel substrate using a two step process of electro-Ni plating followed by pack aluminising at 650 °C. The coating was tested in 100% steam to assess its resistance against steam oxidation at 650 °C using a purpose-built rig for steam oxidation tests. The data obtained were compared with those measured from air oxidation test at the same temperature. It was revealed that steam is a more severe oxidising environment than air for the coating. Oxidation kinetics and degradation mechanisms affecting the lifetime of the coating were discussed.

Abstract: This paper originates from a large EU programme designed to produce high performance coatings with superior mechanical and corrosion resistance properties to enhance high temperature corrosion behaviour of TiAl based alloy (Ti45Al8Nb).The paper here is concerned with studies of the hot corrosion behaviour of Ti – Aluminide alloys (Ti45Al8Nb mainly -TiAl with small amount 2 (Ti3Al)) coated with three coatings: (1) TiAlYN/CrN coating, (2) CrAl with 2%YN addition [1,2] (3) TiAlN with Al2O3 overlayer. Hot corrosion was induced by spraying salts mixture of 80%Na2SO4/20%NaCl with melting point around 700oC [1] [2] on heated sample surfaces, and subsequently heating the sprayed samples in a furnace at 750oC for various times. The extent of degradation, assessed by weight changes and examination by OM (Optical Microscope), SEM (Scanning Electron Microscope), and EDX (Energy Dispersive X-Ray Analysis) indicated that all samples suffered hot corrosion attack to various degrees. TiAlN with Al2O3 overlayer had the best corrosion resistance.We shall discuss these results within a mechanistic framework of hot corrosion degradation and describe their implications.

Abstract: This paper discusses the design and development of sulphidation resistant coatings. The first section discusses the rationale for designing and developing such coatings. The rationale for selecting the coating systems has been derived from our work on the HT sulphidation behaviour of MCrAlYX (M=Co, or Co-Fe and X=V, Nb, Mo and W) type of coating alloys. This work has allowed the establishment of the mechanisms of sulphidation and led to the choice of the coating systems discussed here. The second section describes the sulphidation performance of several selected coatings, single and multilayer, deposited on Ti, TiAl and Ni-based alloys at 750-850oC in environments of low oxygen and high sulphur potentials.

Abstract: Nanoscale studies of four important phenomena – in-situ development of high temperature (HT) wear resistant nanostructured surface glaze, the initial stages of oxidation of TiAl intermetallics, the high temperature degradation of DLC coatings and the property change promoted by nano-patterning of a TiO2 surface are described.

Abstract: This paper discusses the design and development of sulphidation resistant coatings. The first section discusses the rationale for designing and developing such coatings. The rationale for selecting the coating systems has been derived from our work on the HT sulphidation behaviour of MCrAlYX (M=Co, or Co-Fe and X=V, Nb, Mo and W) type of coating alloys. This work has allowed the establishment of the mechanisms of sulphidation and led to the choice of the coating systems discussed here. The second section describes the sulphidation performance of several selected coatings, single and multilayer, deposited on Ti, TiAl and Ni-based alloys at 750-850oC in environments of low oxygen and high sulphur potentials.