Materials Science and Engineering Commons^™

Evaluation Of Thermal Stability Of Ausferrite In Austempered Ductile Iron Using Differential Scanning Calorimetry, Karl Warsinski

Dissertations, Master's Theses and Master's Reports

Austempered Ductile Iron (ADI) is prone to changes in microstructure and mechanical properties when exposed to elevated service temperatures. Differential Scanning Calorimetry has been used to evaluate the stabilizing effects of copper, nickel, molybdenum, and cobalt on the ausferrite structure. Previous studies have conflated the effects of various alloy additions, and little effort has been made to systematically catalog the effects of individual elements. The focus of the current research has been to identify alloying elements that more strongly stabilize the ausferrite structure in order to improve service life of ADI at elevated temperatures. Nickel has been shown to have …

Structural Characteristics And Corrosion Behavior Of Bio-Degradable Zn-Li Alloys In Stent Application, Shan Zhao

Dissertations, Master's Theses and Master's Reports

Zinc has begun to be studied as a bio-degradable material in recent years due to its excellent corrosion rate and optimal biocompatibility. Unfortunately, pure Zn’s intrinsic ultimate tensile strength (UTS; below 120 MPa) is lower than the benchmark (about 300 MPa) for cardiovascular stent materials, raising concerns about sufficient strength to support the blood vessel. Thus, modifying pure Zn to improve its mechanical properties is an important research topic.

In this dissertation project, a new Zn-Li alloy has been developed to retain the outstanding corrosion behavior from Zn while improving the mechanical characteristics and uniform biodegradation once it is implanted …

Microstructural Evolution And Mechanical Properties Of Zn-Ti Alloys For Biodegradable Stent Applications, Zhiyong Yin

Dissertations, Master's Theses and Master's Reports

Stents made of biodegradable metallic materials are increasingly gaining interest within the biomaterials field because of their superior mechanical properties and biodegradation rates as compared to polymeric materials. Zinc and its alloys have been developed and investigated as possible candidates for biodegradable stent applications in the last five years. This study intended to formulate and characterize a new series of Zn-Ti alloys, with titanium additions of less than 1-3 wt%, with the primary objective to develop and select an alloy that meets benchmark values of mechanical properties for biodegradable stents. A series of Zn-Ti alloys was formulated through vacuum induction …

Controlling Properties Of Agglomerates For Chemical Processes, Joseph A. Halt

Dissertations, Master's Theses and Master's Reports

Iron ore pellets are hard spheres made from powdered ore and binders. Pellets are used to make iron, mainly in blast furnaces. Around the time that the pelletizing process was developed, starch was proposed as a binder because it’s viscous, adheres well to iron oxides, does not contaminate pellets and is relatively cheap. In practice, however, starch leads to weak pellets with rough surfaces – these increase the amount of dust generated within process equipment and during pellet shipping and handling. Thus, even though the usual binder (bentonite clay) contaminates pellets, pelletizers prefer it to starch or other organics.

This …