Search Results for bioceramic coatings

This article focuses on the directed-energy deposition (DED) additive manufacturing (AM) technique of biomedical alloys. First, it provides an overview of the DED process. This is followed by a section describing the design and development of the multiphysics computational modeling of the layer-by-layer fusion-based DED process. A brief overview of the primary governing equations, boundary conditions, and numerical methods prescribed for modeling laser-based metal AM is then presented. Next, the article discusses fundamental concepts related to laser surface melting and laser-assisted bioceramic coatings/composites on implant surfaces, with particular examples related to biomedical magnesium and titanium alloys. It then provides a review of the processes involved in DED of biomedical stainless steels, Co-Cr-Mo alloys, and biomedical titanium alloys. Further, the article covers novel applications of DED for titanium-base biomedical implants. It concludes with a section on the forecast of DED in biomedical applications.

Ceramics are used widely in a number of different clinical applications in the human body. This article provides a brief history of the bioceramics field and discusses the classification of bioceramics. These include bioinert ceramics, bioactive ceramics, and bioresorbable ceramics. The article describes third-generation bioceramics, classified by Hench and Polak, such as silicate-substituted hydroxyapatite and bone morphogenic protein-carrying calcium phosphate coatings. It reviews several examination methods used to test the biocompatibility of ceramics, namely, biosafety testing, biofunctionality testing, bioactivity testing, and bioresorbability testing.

This article focuses on ceramics, glasses, glass-ceramics, and their derivatives, that is, inorganic-organic hybrids, in the forms of solid or porous bodies, oxide layers/coatings, and particles with sizes ranging from nanometers to micrometers, or even millimetres. These include inert crystalline ceramics, porous ceramics, calcium phosphate ceramics, and bioactive glasses. The article discusses the compositions of ceramics and carbon-base implant materials, and examines their differences in processing and structure. It describes the chemical and microstructural basis for their differences in physical properties, and relates the properties and hard-tissue response to particular clinical applications. The article also provides information on the glass or glass-ceramic particles used in cancer treatments.

This article summarizes the understanding of the mechanisms and mechanical effects of fatigue processes in highly brittle materials, with particular emphasis on ceramics. It provides a discussion on room-temperature fatigue crack growth in monolithic ceramics, transformation-toughened ceramics, and ceramic composites under cyclic compression. The cyclic damage zones ahead of tensile fatigue cracks, crack propagation under cyclic tension or tension-compression loads, and elevated-temperature fatigue crack growth in monotonic and composite ceramics, are discussed. The article presents ceramic fatigue data for fatigue crack growth testing and concludes with a discussion on life prediction for ceramics or ceramic-matrix composites.

This article presents a detailed account of the processes involved in vat-photopolymerization-based fabrication of ceramics, namely bioceramics, structural ceramics, piezoelectric ceramics, optical ceramics, and polymer-derived ceramics. Information and methods of material preparation, curing characteristics, green-part fabrication, property identification, process design and planning, and quality control and optimization are introduced. The article also provides information on postprocessing techniques, namely debinding and sintering, as well as on the phenomenon of shrinkage and compensation.

Structural applications for advanced ceramics include mineral processing equipment, machine tools, wear components, heat exchangers, automotive products, aerospace components, and medical products. This article begins with an overview of the wear-resistant applications and the parameters affecting wear of ceramics, namely, hardness, thermal conductivity, fracture toughness, and corrosion resistance. The next part of the article addresses temperature-resistant applications of advanced ceramics. Specific applications of ceramic materials addressed include cutting tools, pump and valve components, rolling elements and bearings, paper and wire manufacturing, biomedical implants, heat exchangers, adiabatic diesel engines, advanced gas turbines, and aerospace applications.

The use of 3D bioprinting techniques has contributed to the development of novel cellular patterns and constructs in vitro, ex vivo, and even in vivo. There are three main bioprinting techniques: inkjet printing, extrusion printing (also known as bioextrusion), laser-induced forward transfer (LIFT) printing, which is also known as modified LIFT printing, matrix-assisted pulsed-laser evaporation direct write, and laser-based printing (laser-assisted bioprinting, or biological laser printing). This article provides an overview of the LIFT process, including the LIFT process introduction, different implementations, jetting dynamics, printability phase diagrams, and printing process simulations. Additionally, materials involved during LIFT are introduced in terms of bioink materials and energy-absorbing layer materials. Also, the printing of single cells and 2D and 3D constructs is introduced, showcasing the current state of the art with the ultimate goal for tissue- and organ-printing applications.

This article outlines the selection criteria for choosing an implant material for biomedical devices in orthopedic, dental, soft-tissue, and cardiovascular applications. It details the development of various implants, such as metallic, ceramic, and polymeric implants. The article discusses specific problems associated with implant manufacturing processes and the consequent compromises in the properties of functionally graded implants. It describes the manufacturing of the functionally-graded hip implant by using the LENS process. The article reviews four different types of tissue responses to the biomaterial. It discusses the testing methods of implant failure, such as in vitro and in vivo assessment of tissue compatibility.

Biomaterials are the man-made metallic, ceramic, and polymeric materials used for intracorporeal applications in the human body. This article primarily focuses on metallic materials. It provides information on basic metallurgy, biocompatibility, chemistry, and the orthopedic and dental applications of metallic biomaterials. A table compares the mechanical properties of some common implant materials with those of bone. The article also provides information on coatings, ceramics, polymers, composites, cements, and adhesives, especially where they interact with metallic materials.

Lasers evolved as a versatile materials processing tool due to their advantages such as rapid, reproducible processing, chemical cleanliness, ability to handle variety of materials, and suitability for automation. This article focuses on state-of-the-art laser applications to improve tribological performance of structural materials in lubricated and nonlubricated environments. It discusses the fundamentals of various laser materials interactions and reviews laser-based surface-modification strategies, including laser surface heating and melting, laser-synthesized coatings, and laser-based design approaches such as laser patterning and dimpling. Laser-surface modification of novel materials, such as high-entropy alloys and metallic glasses, is explored. The article provides an overview of hybrid techniques involving laser as a secondary tool, as well as a discussion on the improved capabilities of laser surface engineering for tribological applications by means of integrated computational process modeling.

Calcium phosphates react to form more stable salts in aqueous solutions. This phenomenon has been applied to the solidification process for the dental and medical cement calcium phosphate cement, which consists of multiple phases of calcium phosphates and calcium salts; solidification occurs by the formation of hydroxyapatite. Dicalcium phosphate consists of crystal water along with anhydrous and dihydrate salts. This article summarizes research achievements regarding dicalcium phosphate dihydrate (DCPD) production with controlled morphology and reactivity, including effects of an additive and of production conditions on precipitation. It also summarizes achievements made in the hybridization of nano-apatite onto DCPD particles.

Hydroxyapatite (HA) is one of the most popular materials in tissue scaffold engineering due to its similarity to the nature of human bone; it accounts for more than half of the total weight of the latter. Selective laser sintering (SLS) is an additive manufacturing method that is used in producing tissue engineering parts from HA feedstocks. This article provides a brief overview of the process itself, along with a detailed review of HA-based tissue engineering applications using SLS. Discussion on the various polymer composites is presented. A detailed overview of selected publications on HA-based SLS studies is listed, which provides insight regarding technical aspects of processing HA powder feedstocks.

One of the most frequently cited advantages of ceramics in dentistry relates to aesthetics, and the same applies for dental implants. Zirconia has emerged as the material of choice for nonmetal implants. This article introduces the reader to zirconia as an implant material, its properties, manufacturing processes, and the particular surface modifications and treatments that have rendered its surfaces biologically compatible with peri-implant soft and hard tissues.

The highly irregular morphologies of ceramic powder particles due to their process history present a challenge to binder jetting additive manufacturing (BJ-AM) ceramic powder feedstock processability, but knowledge of powder metallurgy of ceramics benefits the development and analysis of the BJ-AM ceramic processes. Understanding BJ-AM process principles and ceramics processing challenges requires reviewing a number of fundamental principles, which this article delineates. The discussion covers the processability considerations, a brief summary of some fundamental aspects of modeling of liquid permeation in the powder bed, and process capabilities and advantages of BJ-AM technology.

This article reviews various rapid prototyping (RP) processes such as stereolithography, powder sintering, hot melt extrusion, sheet lamination, solid ground curing, and three-dimensional printing. It discusses the various material prototypes produced by RP technology. The list of materials includes particulate and fiber-reinforced polymers, ceramic-matrix composites, and metal-matrix composites. The article also provides information on freeform-fabrication techniques for composite part lay-up.

Stainless steels are used for medical implants and surgical tools due to the excellent combination of properties, such as cost, strength, corrosion resistance, and ease of cleaning. This article describes the classifications of stainless steels, such as austenitic stainless steels, martensitic stainless steels, ferritic stainless steels, precipitation-hardening stainless steels, and duplex stainless steels. It contains a table that lists common medical device applications for stainless steels. The article discusses the physical metallurgy and physical and mechanical properties of stainless steels. Medical device considerations for stainless steels, such as fatigue strength, corrosion resistance, and passivation techniques, are reviewed. The article explains the process features of implant-grade stainless steels, including type 316L, type 316LVM, nitrogen-strengthened, ASTM F1314, ASTM F1586, ASTM F2229, and ASTM F2581 stainless steels.

This article presents a general description of pulsed-laser deposition. It describes the components of pulsed-laser deposition equipment. The article also discusses the effects of angular distribution of materials. Finally, the article reviews the characteristics of high-temperature superconductors and ferroelectric materials.

Sintering provides the interparticle bonding that generates the attractive forces needed to hold together the otherwise loose ceramic powder mass. It also improves hardness, strength, transparency, toughness, electrical conductivity, thermal expansion, magnetic saturation, corrosion resistance, and other properties. This article discusses the fundamentals of sintering and its effects on pore structures and particle density. It addresses some of the more common sintering methods, including solid-state, liquid-phase, and gas pressure sintering, and presents alternative processes such as reaction sintering and self-propagating, high-temperature synthesis. It also describes several pressure densification methods, including hot isostatic pressing, gas pressure sintering, molten particle deposition, and sol-gel processing. The article concludes with a section on grain growth that discusses the underlying mechanisms and kinetics and the relationship between grain growth and densification.

Total joint replacement in orthopedic surgery can be achieved by excision, interposition, and replacement arthroplasty. This article details the most common materials used in total replacement synovial joints: metals, ceramics, and ultrahigh molecular weight polyethylene (UHMWPE). The principal physical properties and tribological characteristics of these materials are summarized. The article discusses pin-on-disk experiments and pin-on-plate experiments for determining friction and wear characteristics. It explains the use of various types of joint simulators, such as hip joint simulators and knee joint simulators, to evaluate the performance of engineering tribological components in machine simulators. The article concludes with a section on the in vivo assessment of total joint replacement performance.

Additive manufacturing (AM), also referred to as three-dimensional printing or rapid prototyping, is a set of technologies that has rapidly evolved and has drawn much research attention in the manufacturing of high value-added products. This article focuses on dentistry, one of the fields in which AM has gained much traction. It discusses the AM processes used to produce dentures, crowns, and bridges. Digitization techniques, which are the first step and provide the CAD model for AM processes, are presented. Scanning technologies that are widely used in dental manufacturing are presented in detail, and the strengths and weaknesses of each process within their applications are discussed. AM processes are discussed in detail, and the materials that are widely used in AM-embedded dental manufacturing are briefly surveyed. The final section concludes with remarks and a preview of future research and practice directions.