Materials: Book of Abstracts最新文献

{"title":"Abrasion of Steel by Diamondlike Carbon Coatings","authors":"S. Harris","doi":"10.1115/imece2000-2680","DOIUrl":"https://doi.org/10.1115/imece2000-2680","url":null,"abstract":"\u0000 Thin ceramic coatings can increase the fatigue lifetime of bearings and gears, possibly by polishing their counterparts and reducing stresses from asperities. Thus, a coating’s ability to polish or abrade may determine its usefulness. Yet there has been little work examining factors which control the abrasiveness of such coatings. We have analyzed the abrasiveness of diamondlike carbon and boron carbide coatings against steel for this study. We find an extremely steep dependence of abrasiveness on hardness. We show that coating roughness with horizontal features on the nanometer-scale is strongly correlated with abrasiveness, while roughness with horizontal features on the micron-scale is not correlated with abrasiveness. The nano-scale—but not the micro-scale—structure is quickly obliterated by sliding against steel, explaining the drastic reduction with time in the abrasiveness of the coating that we observe. We derive quantitative scaling relationships that show how the time dependence of the abrasion rate varies with important parameters of sliding wear, and we use these relationships to predict abrasion kinetics for new experiments. Detailed modeling of the stresses present during abrasion leaves some important questions unanswered.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130844613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Degradation of the Mechanical Properties of Aluminide Coatings as a Result of Thermal Cycling","authors":"M. Walter, Hyungjun Kim","doi":"10.1115/imece2000-2687","DOIUrl":"https://doi.org/10.1115/imece2000-2687","url":null,"abstract":"\u0000 Thermal barrier coatings (TBCs) are typically composed of a ceramic top coat, a thermally grown oxide, and an aluminide bond coat. These three layers each have specific roles in protecting super alloy substrates. State-of-the-art TBCs use Zirconia for the ceramic top coat and develop Alumina thermally grown oxide. Although the bond coats almost universally contain aluminides, their composition and processing vary greatly. In this work, a platinum aluminide bond coat system which was processed using an unactivated pack cementation process is studied. This bond coat system was formed on 1 inch diameter CMSX-4 super alloy disks.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115996092","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mechanical Failure of Artificial Joint Materials: Wear and Fatigue","authors":"L. Topoleski","doi":"10.1115/imece2000-2656","DOIUrl":"https://doi.org/10.1115/imece2000-2656","url":null,"abstract":"\u0000 Total artificial joint replacements are one of the most effective treatments for arthritis. Artificial joints are used to replace damaged cartilage and act as low-friction articulating materials in joints. During normal human walking, some of the materials used for artificial knee and hip replacements are subjected to both sliding articulation (relative motion) and cyclic loading. A common example is the CoCrMo alloy femoral surface of an artificial knee that articulates against an ultra-high-molecular-weight-polyethylene (UHMWPE) component. Other materials do not experience relative motion (at least not intentionally) and are subjected to only cyclic loading. An example is the poly(methyl methacrylate) or PMMA bone cement used to fix components of artificial joints into bones. In the case of articulating materials, both surfaces are susceptible to wear, from both second-body and third body (in the presence of abrasive particles) mechanisms. Wear of the UHMWPE has received considerable attention recently, since the polymer wear is far more obvious than the metal wear. The Biomaterials field is developing an understanding of the wear mechanisms and how to enhance the wear resistance of UHMWPE. The wear of the metal components has not received as much attention, yet materials wear as a couple; both surfaces play a role in the overall wear. In the UMBC Laboratory for Implantable Materials, we are investigating the mechanisms of CoCrMo alloy wear, and the effect of worn metal components on the wear of UHMWPE. Understanding the wear mechanisms of metal components may help to extend the life of artificial joints by allowing new articulating material combinations and joint designs. For non-articulating materials, fatigue failure is a primary concern. Fatigue of metal components is relatively rare. In the distal portion of an artificial hip, the metal hip stem is fixed into the bone by a layer of PMMA bone cement. The PMMA bone cement is far weaker and less resistant to fracture and fatigue than either the bone or the metal, and thus may be considered the mechanical “weak link” in cemented total joints. We are investigating the fatigue properties of PMMA bone cements, and studying the mechanisms of fatigue crack initiation. If we can determine how fatigue cracks start in bone cement, we may be able to develop, for example, new surgical procedures (e.g., bone preparation) that will reduce the likelihood of fatigue failure. New formulations of bone cement have been developed for both joint fixation, and also for bone repair or replacement. Understanding the failure mechanisms of bone cements may enable safe and effective new uses for new bone cements, and extend the lives of cemented artificial joints.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124367446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A New Statistical Biomechanics Modeling of Physical and Biochemical Bone Strength Parameters","authors":"A. Soboyejo, K. Nestor","doi":"10.1115/imece2000-2698","DOIUrl":"https://doi.org/10.1115/imece2000-2698","url":null,"abstract":"\u0000 New multiparameter biomechanics models are developed in this work for the characterization of bone strengths in broiler chickens and turkeys, as functions of the major physical and biochemical parameters, which can contribute to mechanical properties of bone strengths in these birds, under good management practices. Theoretical and experimental methods have been developed in this study to model bone strength as functions of (a) the physical parameters only and (b) the biochemical parameters only, which can affect bone strength. The choice of any particular methodology will depend on the availability of either the physical or biochemical parameters, which can be obtained from experimental data. Possible useful practical applications of the statistical biomechanics principles developed in this technical paper, particularly in the field of bone strength enhancement in turkeys and broiler chickens will be discussed.\u0000 In view of the problems described, the major objectives of the present study are as follows:\u0000 (1) To develop new multiparameter biomechanics models for the characterization of bone strengths in turkeys and broiler chickens as functions of the major physical only, or biomechanical parameters only, which can contribute to bone strength in these birds, under conditions of good management of these birds. This study will consider only the compressive buckling as the mode of structural failure in the cellular material of the bone.\u0000 (2) To highlight briefly the possible practical applications of the statistical biomechanics principles, which will be developed in this study to the genetic improvement of bone strengths in broiler chickens and turkeys.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133387829","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Towards Reliable Thermal Spray Coatings: An Integrated Approach","authors":"S. Sampath","doi":"10.1115/imece2000-2692","DOIUrl":"https://doi.org/10.1115/imece2000-2692","url":null,"abstract":"\u0000 Thermal sprayed coatings are used extensively in engineering components for a variety of protective coating applications. Thermal spraying is a highly dynamic process resulting from rapid heating /accelerating of powder particles in a flame, followed by impact and rapid solidification of the droplets (splats). A splat resulting from the flattening of an individual droplet is the basic building block (unit cell) of the thermal sprayed microstructure. Phase and microstructure of the splats (intrinsic) and the integration of the splats (extrinsic) are both affected by processing condition and the properties of a plasma sprayed deposit are directly related to this complex anisotropic microstructure. These affect both performance and reliability of sprayed surfaces.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"50 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131206752","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Tooth as a Basis for Biomimetic Design","authors":"V. Thompson, Stephen Kao, Ivory Kirkpatrick","doi":"10.1115/imece2000-2663","DOIUrl":"https://doi.org/10.1115/imece2000-2663","url":null,"abstract":"\u0000 Teeth are uniquely capable of withstanding high forces (>200 N) with small contact area (< 0.5 mm2) and a high number of fatigue cycles (> 107) with little evidence of damage. Yet the tooth is comprised of an outer very brittle, anisotropic, highly crystalline enamel layer supported by an inner soft, but tough dentin. These structures are joined by a small (appoximately 30 microns wide) transition zone called the dento-enamel junction (DEJ). The DEJ plays a critical role in transfer of stress across the layers of the tooth. How the enamel-dentin complex (EDC) comprised of these layers and the DEJ is able to withstand the high contact loads and high cycle fatigue is not well understood. An understanding of the interplay of the various components would serve as the basis for design of dental ceramic or resin based composite crowns capable of service lives approaching those on natural teeth. Current all ceramic crowns have high failure rates (1–5% per yr) on molar teeth and improved performance is required before CAD-CAM restorations can be successful.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133916772","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal Release From Ti-6Al-4V Posterior Cervical Spine Plates: A Computational and Experimental Study in the Canine Model","authors":"M. Villarraga","doi":"10.1115/imece2000-2659","DOIUrl":"https://doi.org/10.1115/imece2000-2659","url":null,"abstract":"\u0000 The use of Ti-6Al-4V for spinal implants has increased due to its advantageous mechanical properties, biocompatibility, corrosion resistance, and compatibility with MRI procedures. The release of metal ions or particulates, which can result from mechanical loads imposed on the implant, can affect the degree of biocompatibility of spinal implants, possibly influencing their clinical performance. In this project, the titanium metal release from Ti-6Al-4V posterior cervical spine plates was examined using a computational and experimental approach in the canine model.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132295165","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Functional Analysis of Bone-Biomaterial Interface","authors":"R. Tuan","doi":"10.1115/imece2000-2675","DOIUrl":"https://doi.org/10.1115/imece2000-2675","url":null,"abstract":"\u0000 Proper function and long-term stability of orthopaedic implants depend on the intimate association between bone cells and the implant biomaterial, a process known as osseointegration. Understanding the processes responsible for the establishment and maintenance of a functional bone-biomaterial interface and how these processes may be enhanced is crucial to the rational design and optimization of prosthetic devices. We have utilized cellular, molecular, and high-resolution imaging approaches to analyze the mechanistic basis of bone-biomaterial interactions. Specifically, we have characterized the initial adhesion of osteoblasts in terms of kinetics and relationship to the surface topography and chemistry of the biomaterials, particularly the cobalt-chrome and titanium alloys commonly used to fabricate orthopaedic prostheses. Results from these studies indicate that the long-term performance of osteoblasts adherent to biomaterials is crucially dependent on the characteristics of the initial adhesion step. Furthermore, osteoactive factors such as members of the transforming growth factor-β superfamily, including TGF-β1 and BMP-2, significantly enhance osteoblast cell adhesion. The molecular components responsible for the adhesion process include extracellular matrix proteins (e.g. fibronectin and collagen type I) and their cognate membrane receptors, the integrins. Our recent studies reveal that specific downstream, intracellular signaling events are also activated as a result of osteoblast adhesion, and that these signaling events are coupled to signal transduction mechanisms mediating growth factor activity. These events in combination regulate the continued expression and maintenance of the osteoblastic phenotype of the adherent cells, resulting in matrix maturation and mineralization, hallmarks of the bony tissue. Our current efforts focus on defining the target molecular pathways responsible for bone cell functioning on biomaterials, and the identification of critical biological and material parameters to optimize long-term osteoblast function and interaction with orthopaedically relevant biomaterials. The information gathered from these studies should provide a rational basis for the design of optimal implant biomaterials. (Supported in part by the NIH and the Annenberg Foundation)","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"115047350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The Functional Performance of Poly Methylmethacrylate Orthopaedic Bone Cement","authors":"P. Prendergast","doi":"10.1115/imece2000-2699","DOIUrl":"https://doi.org/10.1115/imece2000-2699","url":null,"abstract":"\u0000 Materials for fixation of load-bearing implants in the human body should be able to sustain a cyclic load of variable magnitude over an extended period over the remaining lifetime of the parient. A material commonly used for fixation of orthopaedic, dental, and maxillofacial implants is a polymer poly methylmethacrylate (PMMA). However, PMMA does not ideally fulfill this criterion because it undergoes damage accumulation and creep under cyclic loading. This leads to implant loosening and the need for a revision operation.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126098862","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Priorities and Expectations for Surface Engineering: A Personal View","authors":"J. Larsen-Basse","doi":"10.1115/imece2000-2676","DOIUrl":"https://doi.org/10.1115/imece2000-2676","url":null,"abstract":"\u0000 Surface engineering is currently attracting wide attention. The need to engineer surfaces for specific performance requirements has always been present but, until recently, the means available to accomplish this were few. The situation has changed dramatically during the past few decades when the rate, at which new surface modification processes appear, has escalated rapidly. The growth has been driven by synergistic advances in process control, modeling, materials and surface science, and in instrumentation which enables us to closely analyze and observe the surface and the near-surface material in great detail. At this point industrial adaptation of the new processes is lagging somewhat, awaiting maturation of the most promising processes so they can be reliably used in mass production.","PeriodicalId":324509,"journal":{"name":"Materials: Book of Abstracts","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2000-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131150245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}