Search Results for binder material

The use of zinc in corrosion-protective coatings is due to its higher galvanic activity relative to that of steel. Pure zinc dust provides the best sacrificial protection to steel in a galvanic couple. Zinc-rich coatings can be subcategorized according to the type of binder material used, namely, inorganic and organic zinc-rich coatings. Common inorganic binders such as post-cured water-based alkali metal silicates, self-cured water-based alkali metal silicates, and self-cured solvent-based alkyl silicates, are reviewed. The article also compares inorganic and organic zinc-rich coatings, and discusses the concerns regarding zinc-rich coatings.

This article describes the characteristics of zinc-rich coatings that can be subcategorized according to the type of binder material used. It discusses the formulations of zinc-rich coatings with organic binders. The three major groups of inorganic zinc-rich coatings categorized by the Society for Protective Coatings are also discussed. These include postcured water-based alkali metal silicates, self-cured water-based alkali metal silicates, and self-cured solvent-based alkyl silicates. The article concludes with information on comparisons of inorganic with organic zinc-rich coatings.

Cemented carbides belong to a class of hard, wear-resistant, refractory materials in which the hard carbide particles are bound together, or cemented, by a ductile metal binder. Cermet refers to a composite of a ceramic material with a metallic binder. This article discusses the manufacture, composition, classifications, and physical and mechanical properties of cemented carbides. It describes the application of hard coatings to cemented carbides by physical or chemical vapor deposition (PVD or CVD). Tungsten carbide-cobalt alloys, submicron tungsten carbide-cobalt alloys, and alloys containing tungsten carbide, titanium carbide, and cobalt are used for machining applications. The article also provides an overview of cermets used in machining applications.

Cemented carbides, best known for their superior wear resistance, have a range of industrial uses more diverse than that of any other powder metallurgy product including metalworking and mining tools and wear-resistant components. This article discusses raw materials and manufacturing methods used in the production of cemented carbides, the physical and mechanical properties of carbides, and wear mechanisms encountered in service. Emphasis is placed on tungsten carbide-cobalt (WC-Co) or tungsten carbide-nickel (WC-Ni) materials as used in nonmachining applications. Nominal composition and properties of representative cemented carbide grades and their applications are listed in a table.

Consolidation and shaping of grade powders is carried out using several methods, depending on the size, complexity, shape, and quantity of parts required. This article details the powder consolidation methods of carbide powders: uniaxial pressing, cold isostatic pressing, extrusion, green machining, and injection molding.

According to International Organization for Standardization (ISO)/ASTM International 52900, additive manufacturing (AM) can be classified into material extrusion, material jetting, vat photo polymerization, binder jetting, sheet lamination, powder-bed fusion (PBF), and directed-energy deposition. This article discusses the processes involved in polymer powder 3D printing using laser fusion/ sintering and fusing agents and energy, as well as the thermally fused PBF. It provides information on polymer powder parameters and modeling, the powder-handling system, powder characterization, the flowability of powder feedstock, and polymer part characteristics. The article describes the types of polymers in PBF, the processes involved in powder recycling, and the prospects of PBF in AM. In addition, the biomedical application of polyether ether ketone (PEEK) is also covered.

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 discusses two major sintering methods: pressureless and pressure-assisted sintering. Pressureless sintering techniques include vacuum and partial-pressure, hydrogen, and microwave sintering. Pressure-assisted consolidation techniques include overpressure sintering, sintering followed by postsinter hot isostatic pressing, hot pressing, and several rapid hot consolidation techniques. The article describes nitrogen sintering and the sintering of cermets. It reviews the furnaces used for sintering and presents the lubrication removal techniques. The article also outlines the need to control carbon and oxygen to obtain optimal properties and explains microstructure development and grain size control.

This article discusses the process details of metal powder injection molding of microcomponents and the powder particle characteristics of feedstock and property requirements of binders. It reviews important characteristics to be considered in the processing steps: venting, channel diameters, binder segregation, binder degradation, feedstock supply, temperature control, demolding, debinding, and sintering. Finally, the article provides information on powder injection molding mold-filling simulation and two-component powder injection molding, offering a method for high-volume production of microcomponents made of multifunctional materials.

Additive manufacturing (AM) technologies print three-dimensional (3D) parts through layer-by-layer deposition based on the digital input provided by a computer-aided design file. This article focuses on the binder jet printing process, common biomaterials used in this AM technique, and the clinical applications relevant to these systems. It reviews the challenges and future directions of binder-jetting-based 3D printing.

Ceramic-forming processes usually start with a powder which is then compacted into a porous shape, achieving maximum particle packing density with a high degree of uniformity. This article compares and contrasts several forming processes, including mechanical consolidation, dry pressing, cold isostatic pressing, slip casting, tape casting, roll compaction, extrusion, and injection molding. It describes the advantages, equipment and tooling, and material requirements of green machining, the machining of ceramics in an unfired state with the intent of producing parts as close to as possible to their final shape. The article also provides useful information on drying methods, shrinkage, and defects as well as the removal of organic processing aids such as dispersants, binders, plasticizers, and lubricants.

Cemented carbides belong to a class of hard, wear-resistant, refractory materials in which the hard carbide particles are bound together, or cemented, by a soft and ductile metal binder. The performance of cemented carbide as a cutting tool lies between that of tool steel and cermets. Almost 50% of the total production of cemented carbides is used for nonmetal cutting applications. Their properties also make them appropriate materials for structural components, including plungers, boring bars, powder compacting dies and punches, high-pressure dies and punches, and pulverizing hammers. This article discusses the manufacture, microstructure, composition, classifications, and physical and mechanical properties of cemented carbides, as well as their machining and nonmachining applications. It examines the relationship between the workpiece material, cutting tool and operational parameters, and provides suggestions to simplify the choice of cutting tool for a given machining application. It also examines new tool geometries, tailored substrates, and the application of thin, hard coatings to cemented carbides by chemical vapor deposition and physical vapor deposition. It discusses the tool wear mechanisms and the methods available for holding the carbide tool. The article is limited to tungsten carbide cobalt-base materials.

This article focuses on binder-jetting technologies in additive manufacturing (AM) that produce metal artifacts either directly or indirectly. The intent is to focus on the most strategic and widespread uses of the binder jetting technology and review some of the challenges and opportunities for that technology. The discussion includes a historical overview and covers the major steps involved and the advantages of using the binder jetting process. The major steps of the process covered include printing, curing, de-powdering, and sintering.

Inkjet printing is extremely precise in terms of the ejected microdroplets (picoliter volume), contributing an unparalleled lateral resolution. Additionally, the benefits of high-speed deposition, contactless ink delivery, and the use of a range of ink materials endorse this technique as suitable for high-throughput 3D manufacturing. This article provides an overview of inkjet 3D printing (also referred to as 3D inkjetting). It then highlights the major components and accessories used in commercial and laboratory-based 3D inkjet printers. Next, the article describes the process physics of the transient phenomena involved in both binder-jetting- and direct-inkjetting-based 3D printing. It then discusses the scope and advantages of 3D inkjetting in the manufacturing of metallic, ceramic, and polymer-based biomaterials. The article also discusses several approaches and methodologies to examine the in vitro cytocompatibility and in vivo biocompatibility of both binder-jetted and direct-inkjetted scaffolds for biomedical applications. Finally, it discusses the challenges and troubleshooting methodologies in 3D inkjetting of biomaterials.

This article describes part selection, feedstock (powders and binders) characteristics and properties, tool design, and material and tooling for fabrication of metal powder injection molding (MIM) machines. It discusses the process parameters, operation sequence, molding machines, debinding techniques, consolidation (sintering) techniques, advantages, and limitations of MIM.

This article reviews the pattern materials used in investment casting, which can be loosely grouped into waxes and plastics. The patternmaking process, pattern tooling, and pattern and cluster assembly are described. The article also describes the manufacture of ceramic shell molds and cores, detailing the binders and other materials used, as well as the formulation and control of slurries. Methods for pattern removal, mold firing, melting, casting, postcasting treatment, and inspection are explained. After presenting design recommendations for investment castings, the article concludes with information on applications and special versions of the investment casting process.

Cemented carbides are extremely important in corrosion conditions in which high hardness, wear resistance, or abrasion resistance is required. This article describes the effect of binder composition and carbide addition on corrosion behavior of cemented carbides. It lists the examples of their uses in corrosion applications. The article provides information on the selection of cemented carbides for corrosion applications and tabulates the corrosion resistance of cemented carbides in various media. It expounds the oxidation resistance of cemented carbides and presents some tips to improve the properties of tungsten carbide cutting tools. The article also details the coating materials and coating processes of cemented carbides.