On the Development of Novel Advanced Multifunctional Structural Materials

In this presentation, I will present recent research findings on three different areas of materials research: (a) novel structural materials by CO2 sequestration, (b) MAX phases (novel natural laminates) and their application in oil free engines, and (c) advanced manufacturing.
During Part A, I will present recent studies about development of novel multifunctional sustainable materials. In particular, I will present fundamental research for developing novel structural materials by CO2 sequestration (Low Temperature Solidification Technology) and low alkali activation (Low Alkali Fly Ash Cement).  Different components of microstructure, and their correlation with physical properties will be described. From fundamental perspective, carbonate based solids have also aroused intense attention due to their potential for CO2 storage via carbonation of mineral silicates. Recent results show that it is possible to design and fabricate different types novel composites which can have similar, if not better, properties than high performance concrete by CO2 sequestration of mineral silicates. 
During Part B, recent research studies 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 (for example, oil free engines) at 50,000 rpm from RT till 550oC 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 550oC. 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, 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).