1. Tribological and Radiation Shielding Response of Novel Titanium-Boron Nitride Coatings for Lunar Structural ComponentsAluminum (Al) and titanium (Ti) lightweight alloys play a crucial role in space systems due to their exceptional strength-to-weight ratio. However, their premature failure in the presence of lunar regolith and their lack of neutron shielding ability are significant challenges. To address these issues, we have developed air and vacuum plasma-sprayed hBN (hexagonal Boron Nitride) -reinforced titanium coatings with 2 and 10 vol% of hBN. Tribological studies conducted with JSC-1 A lunar regolith simulant revealed a 90 % reduction in wear volume for the Ti/2 vol% hBN coatings compared to conventional materials due to the synergistic action of harder secondary phases and solid lubrication effect of hBN. Additionally, a 27 % enhancement in radiation shielding is obtained based on the mass absorption coefficient (radiation absorbed per sample density and thickness) for VPS Ti/2 vol% hBN coatings.
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2. Wear and neutron shielding resilience of titanium-hexagonal boron nitride coatings against extreme lunar radiation and thermal cyclesTi6Al4V and Al6061 are aerospace alloys used in lunar components but degrade quickly under harsh lunar conditions like extreme temperatures, radiation, and abrasive regolith. To protect them, cryo-milled powders were plasma-sprayed onto substrates, creating hBN-reinforced titanium coatings with 2 and 10 vol% hBN. These coatings were tested under lunar-like thermal cycling, radiation, and combined stresses, showing a 20–40% microhardness increase due to radiation-induced hardening. Wear tests with lunar regolith simulant showed that Ti/2 vol% hBN coatings reduced wear by up to 90%. Neutron shielding also improved by up to 28% due to 10B isotopes. Among tested coatings, VPS Ti/2 vol% hBN proved most effective for lunar protection.
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3. In-situ crack propagation dynamics in multicomponent ultra-high temperature carbidesSolid-solutioning in multicomponent ultra-high temperature ceramics (MC-UHTCs) enhances thermo-mechanical properties beyond those of conventional UHTCs. In this study, MC-UHTCs were synthesized using spark plasma sintering (SPS) with binary to quaternary compositions in the (Ta,Nb,Hf,Ti)C system. Real-time 4-point flexural testing captured failure events like cracking and fracture, revealing that quaternary UHTCs achieved the highest flexural strength (726 MPa) and fracture toughness (4.7 MPa·m0.5), surpassing binary and ternary UHTCs by up to 270%. Microstructural analysis showed solid solutions and defect features that enhanced damage tolerance, positioning quaternary UHTCs as promising materials for hypersonic applications.
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4. Scratch-Induced Wear Behavior of Multi-Component Ultra-High-Temperature CeramicsMulti-component ultra-high-temperature ceramics (MC-UHTCs) are promising for high-temperature applications due to exceptional thermo-mechanical properties, yet their wear characteristics remain unexplored. Herein, the wear behavior of binary (Ta, Nb)C, ternary (Ta, Nb, Hf)C, and quaternary (Ta, Nb, Hf, Ti)C UHTCs synthesized via spark plasma sintering (SPS) is investigated. Gradual addition of equimolar UHTC components improves the wear resistance of MC-UHTCs, respectively, by ~29% in ternary UHTCs and ~49% in quaternary UHTCs when compared to binary UHTCs. Similarly, the penetration depth decreased from 115.14 mm in binary UHTCs to 73.48 mm in ternary UHTCs and 44.41 mm in quaternary UHTCs. This has been attributed to the complete solid solutioning, near-full densification and higher hardness (~up to 30%) in quaternary UHTCs. Analysis of the worn-out surface suggests pull-out, radial, and edge micro-cracking and delamination as the dominant wear mechanisms in binary and ternary UHTCs. However, grain deformation and minor delamination are the dominant wear mechanisms in quaternary UHTCs. This study underscores the potential of MC-UHTCs for tribological applications where material experiences removal and inelastic deformation under high mechanical loading.
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5. Scratch-Induced Deformation Behavior of Wire-Arc Directed Energy Deposited α-TitaniumThis study investigates the scratch response of α-phase commercially pure titanium (cp-Ti) produced via wire arc directed energy deposition (WDED), focusing on the thermal history and directional effects. Progressive scratch tests (1–50 N) revealed heterogeneous wear properties between the top and bottom layers, with the top layer exhibiting higher material recovery (58 ± 5%) and wear volume (5.02 × 10−3 mm3) compared to the bottom layer (42 ± 5% recovery, 4.46 × 10−3 mm3), attributed to slower cooling rates and coarser grains enhancing ductility. The variation in the properties stems from the thermal gradient generated during WDED. Electron backscatter diffraction analysis showed higher kernel average misorientation (KAM) in the bottom layer (0.84° ± 0.49° vs. 0.51° ± 0.44°), affecting plasticity by reducing dislocation and twin boundary mobility. No significant differences were observed between longitudinal and transverse orientations, with coefficients of friction averaging 0.80 ± 0.12 and 0.79 ± 0.13, respectively. Abrasive wear dominated as the primary mechanism, accompanied by subsurface plastic deformation. These findings highlight the significant influence of WDED thermal history in governing scratch resistance and deformation behavior, providing valuable insights for optimizing cp-Ti components for high-performance applications.
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OTHER PROJECTS
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Static Structural Finite Element Analysis (FEA)
CREO SCHEMATICS Conceptualization and Circuit Design
Wear Resistance of Ultra-High Temperature Ceramics
Plasma Sprayed of Coatings Analysis
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Harness Design Routing Optimization
3D Printing of Lunar Regolith with NASA
Scratch Testing of 3D Printed Titanium (WAAM)
Nano-Indentation of Allegator Teeth
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