Browsing by Subject "surface modification"

Now showing 1 - 3 of 3

High Therma
(University of Texas at Austin, 2009-09-15) España, Félix A.; Balla, Vamsi Krishna; Bose, Susmita; Bandyopadhyay, Amit
Surface modification has been used to improve wear resistance, corrosion resistance and thermal barrier properties of metals. However, no significant attempts have been made to improve thermal conductivity by surface modification. In this work, we have examined the feasibility of enhancing thermal conductivity (TC) of stainless steel by depositing brass using Laser Engineered Net Shaping (LENS). The coating increased the TC of the substrate by 65% at 100 C°. Significantly low thermal contact resistance was observed between the coating and the substrate due to minimal dilution and defect free sound interface. Our results indicate that laser processing can be used on low coefficient of thermal expansion metal matrix composites to create feature based coatings to enhance their heat transfer capability.
Investigation of Forged-Like Microstructure Produced by A Hybrid Manufacturing Process
(University of Texas at Austin, 2014) Francis, Romy; Newkirk, Joseph W.; Liou, Frank
Laser Metal Deposition (LMD) is an additive manufacturing technique for manufacturing complex near net shaped components. The grain size of the typical deposition microstructure in case of Ti-6Al-4V can range between 100µm-600µm, which is much larger than that of forged-like microstructures. Friction Stir Processing (FSP) has been investigated as a method for surface modification to form refined microstructure at the surface of the Ti-6Al-4V components manufactured from the LMD method. Integration of FSP and LMD can greatly improve the product properties. Friction stir processing of the laser deposited Ti-6Al-4V deposits was performed and optimum processing parameters were obtained using this hybrid process. The microstructure of the nugget regions obtained in the substrate weld, stir over deposit and deposit over stir experiments is presented. A much decreasing grain size was observed in the dilution zone inside the nugget from the stir surface to the bottom of the dilution zone.
Surface Modification on a Porous Co-Cr Scaffold Fabricated by Selective Laser Melting for Bone Implant Applications
(University of Texas at Austin, 2015) Han, C.J.; Chen, X.; Tan, J.W.; Yao, Y.; Wei, Q.S.; Zhang, Z.; Shi, Y.S.
Cobalt–chromium–molybdenum alloys with porous structures can be fabricated by additive manufacturing technique, which are attractive for use as scaffolds for bone implant applications. However, metallic implant are difficult to bond directly to living bone due to limited implant interface problems. Therefore, surface modification with scaffold material is required to improve bio-compatibility and the interface surface. In this study, a porous Co-Cr scaffold fabricated by selective laser melting was modified by electrodeposition with biocompatible silk fibroin. The surface characteristics of porous scaffold before and after surface modification were evaluated with the atomic force microscopy, scanning electron microscopy, X-ray diffraction, water contact angle measurement. The mechanical properties including elastic modulus and compressive strength, were determined by compression tests.