Colloquium: Dr. Surojit GuptaDr. Surojit Gupta Department of Mechanical Engineering University of North Dakota Grand Forks, ND
On the Development of Novel Advanced Materials
In this presentation, I will present research findings on three different research areas of materials research: (a) advanced manufacturing, (b) MAX phases (novel natural laminates) and their application in oil free engines, and (c) novel structural materials by CO2 sequestration.
During Part A, a novel testing methodology for studying advanced manufacturing, which includes the evaluation of free sintering strain, stress-induced dimensional changes, and weight changes, will be presented. This methodology was developed to determine the critical dimensional changes and thermomechanical response during presintering (i.e., before densification).
During Part B, recent results on MAX phases will be presented. Mn+1AXn (MAX) phases (over 60+ phases) are thermodynamically stable nanolaminates displaying unusual, and sometimes unique, properties. These phases possess a Mn+1AXn chemistry, where n is 1, 2, or 3, M is an early transition metal element, A is an A-group element, and X is C or N. The MAX phases are highly damage tolerant, thermal shock resistant, readily machinable, and with Vickers hardness values of 2–8 GPa, are anomalously soft for transition metal carbides and nitrides.MAX phases display nonlinear, hysteretic, elastic behavior due to kink band formation in the basal planes. The Wd (energy dissipated per unit volume per cycle)of these crystalline solids are comparable to most woods. The composites of MAX phases with metals (MAXMET) are also important from both fundamental and applied perspective. I have comprehensively studied the tribology of MAX and their composites. As a part of this study, it was demonstrated that MAX Phase-based composites can be used as shafts against SA (Super Alloys) foils for different foil bearing applications at 50,000 rpm from RT till 550o C during thermal cycling. Earlier, despite several years of research there were no structural materials which could be used as a solid lubricant in the temperature range of RT to 550o C. Thus, there is a huge potential that these materials can be used for different tribological and engineering systems, for example, air-foil bearings, gas turbine seals, cylinder wall/piston ring lubrication for low-heat rejection diesel engines, various furnace components, among many others.
During Part C, it will be shown that by using hydrothermally processed mineral silicates, it is possible to design and fabricate different types novel composites which can have similar, if not better, properties than high performance concrete by using CO2 sequestration. Novel damage resistant solids can also be designed by exploiting the presence of interfaces between different layers.