Mahfujur Rahman

Novel, Nanoporous Silica and Titania Layers Fabricated by Magnetron Sputtering

Composite asymmetric membranes are fabricated through the deposition of submicrometer thick (100 nm) silica (SiO(2)) and titania (TiO(2)) films onto flat nanoporous silica and zirconia substrates by magnetron sputtering. The deposition conditions for both coating types were systematically altered to determine their influence on the deposited coating morphology and thickness. Ideal He/N(2) gas selectivity was measured for all of the membranes. The TiO(2) coatings, when deposited onto a ZrO(2) support layer with a pore size of 3 nm, formed a long columnar grain structure with average column diameter of 38 nm. A similar columnar structure was observed for TiO(2) coatings deposited onto a SiO(2) support layer with a pore size of 1 nm. Under the same conditions, SiO(2) coatings, deposited onto the same SiO(2) supports, formed a closely packed spherical grain structure whereas, when deposited onto ZrO(2) supports, the SiO(2) coatings formed an open grain structure. The average SiO(2) grain diameter was 36 nm in both cases. This preliminary investigation was aimed at studying the effect of sputtering parameters on the density and morphology of the deposited coatings. For the depositions carried out, the coating material was found to be very dense. However, the presence of grain boundaries resulted in poor ideal He/N(2) separation efficiencies.

Adhesion performance of TiN coating with amorphous NiTi alloy interlayer onto 316L stainless biosteel deposited by sputtering process

Abstract In the present study, TiN coatings were deposited with and without NiTi interlayer onto 316L stainless steel substrates to observe the effect of amorphous NiTi layer on the adhesion properties of TiN coatings. The deposition technique was carried out at a temperature (100–150°C) without any substrate heating to form the amorphous NiTi coating, using the closed field unbalanced magnetron sputtering system. The qualitative and quantitative adhesion properties of TiN coatings with and without amorphous NiTi interlayer were measured using the Rockwell C test, the scratch test and the pull-off test. This research demonstrates how the amorphous NiTi interlayer improved the adhesion of TiN coating when a thickness of the NiTi interlayer applied was equal to 0·5 μm. A thin layer of amorphous NiTi coating was shown to exert a significant influence over the adhesion performance of the TiN coatings and demonstrating its suitability for the tribological applications.

Effect of Annealing Treatment on the Wear Properties of Ni Rich NiTi Alloy Coatings

In the present study, NiTi alloy coatings were deposited onto AISI 316L stainless steel substrates using the Closed Field Unbalanced Magnetron Sputtering (CFUBMS) system. The as-deposited NiTi alloy coating was Ni rich NiTi alloy with a composition of 44.1 at. % of Ti and 55.9 at. % of Ni and demonstrated an amorphous structure. The post-annealing treatment of the as-deposited Ni rich NiTi alloy coating was successfully produced a crystalline structure. The as-deposited and the annealed Ni rich NiTi alloy coatings were characterized to determine the effect of the annealing process on their wear properties. The Ni rich NiTi phases and structure were determined by XRD. Wear morphology was investigated using the pin-on-disk wear test. The existence of a TiO2 rutile layer with a combination of the Ni3Ti and NiTi B2 parent phases, that formed during the annealing process produced a significant improvement over the wear performance compared to the as-deposited Ni rich NiTi SMA coating. The post-sputtered annealing process at the annealing temperatures of 550°C for a period of 60 minutes and 600°C for a period of 30 minutes succeeded in increasing the adhesion and wear resistance of the Ni rich NiTi coating. The findings show the potential the post-sputtering annealing process in creating an excellent structure of NiTi coating which demonstrates significant wear resistance properties for tribological applications.

1.02 – Techniques for Assessing the Properties of Advanced Ceramic Materials

Advanced ceramics are emerging as ideal materials for a wide range of engineering applications, such as cutting tools, engine, turbines, space vehicles, and biomedical applications, among others, due to their superior properties as compared to traditional ceramics. The properties of advanced ceramics mainly differ from those of traditional ceramics in their processing, composition, and microstructure. Therefore, in order to get a better understanding of advanced ceramics and to further develop them for particular engineering applications, extensive use must be made of the characterization method for evaluating enhanced microstructural, mechanical, electrical, optical, and biomedical properties. The objective of this chapter is to give a brief overview of characterization techniques that are commonly used to evaluate the diverse properties of the advanced ceramics.

Mechanical Performance of the Annealed NiTi Shape Memory Alloy Coating onto 316L Stainless Bio-Steel

This paper presents the mechanical performance of the annealed NiTi Shape Memory Alloy (SMA) coating deposited onto 316L stainless steel substrate. The as-deposited SMA coating, Ni55.9 Ti44.1, showed an amorphous behaviour. The crystalline NiTi (SMA) coating was produced by annealing the as-deposited NiTi with a thickness about 2.0 µm, at above its crystallisation temperature in a vacuum ambient. The annealed NiTi coatings were characterised to determine the effect of the annealing parameters on their mechanical behaviour. The NiTi phases and structures were determined by x-ray diffraction (XRD) and scanning electron microscopy (SEM) whereas the mechanical properties were measured using the Rockwell C adhesion test. Three main phases; NiTi B2 parent phase, Ni3Ti and TiO2 were found in the annealed samples and the intensities of each phase were dependent on the annealing temperature and annealing time. Each phase significantly affected the mechanical behaviour of the coatings. Higher intensities of Ni3Ti and TiO2 phases were believed to contribute to the low adhesion of the annealed NiTi coatings due to their brittle properties. The annealing parameters; 600 °C for durations of 30 min was considered as the optimum parameter, yielding no fine cracks at the Rockwell C indentation interface compared to other samples at high magnification under the SEM. Adding a hard top layer of TiN would potentially provide a hard coating with an interlayer capable of absorbing impact which would be very suitable for ball joints used in hip replacement therapy.

Health and Safety Issues in Emerging Surface Engineering Techniques

Surface engineering has become a well-established technology and is an extremely versatile means of improving component performance in different science and engineering applications. As with any manufacturing technology, surface engineering processes present environmental, health, and safety hazards as well. Owing to the increasing stringent legislations and national and international standards on health and safety, a number of emerging surface engineering processes (e.g., physical vapor deposition) have been developed recently. Although health and safety concerns involved in traditional surface engineering processes (e.g., electroplating) have been minimized to a great extent in the emerging processes; however, new hazards and risks have also been introduced during this development. The motivation for writing this chapter is to give a brief overview on the different aspects of health and safety issues, which arise from emerging surface engineering processes. In addition, the necessary steps that need to be considered to address the health and safety concerns associated with the emerging processes have been discussed.