Search Results for piston rings

Chemical vapor deposition (CVD) of pyrolytic chromium carbide coatings (PCCCs) is proving to be a viable alternative to hard chrome plating used on cylinder piston group components. This article discusses the development and optimization of a CVD process for depositing PCCCs on piston rings and cylinder sleeves. It evaluates the coatings based on friction, wear, and adhesion properties in comparison with coatings produced by other methods.

Active screen plasma nitriding and nitrocarburizing are relatively new processes in which a plasma discharge is applied to a metal screen surrounding the workload, generating highly reactive gas species that flow to the component surface. The active screen also radiates heat, resulting in a uniform temperature throughout the load. This article provides an overview of the two processes and presents examples of their use on stainless steel piston rings (nitriding) and 4142 and 1045 steels (nitrocarburizing).

An ultrafast, efficient industrial-scale boriding process can drastically reduce costs, increase productivity, and improve the performance and reliability of a variety of machine parts. This article describes a novel, environmentally friendly technology that enables treating thousands of industrial components in one batch, without creating solid or liquid waste and gaseous emissions.

Although computer modeling of friction phenomena continues to improve, bench-scale and subscale tribotesting remain important in selecting materials, surface treatments, and lubricants for automotive applications.

A new laser arc method is being used to apply a hard carbon coating to engine components on the production line. This article reports on work to produce hydrogen-free tetrahedral amorphous carbon coatings on an industrial scale with consistent quality.

Innovations built into a new plasma spray torch address shortcomings of previous axial injection equipment.

Conventional manufacturing from wrought bar stock typically involves extensive machining, creates significant material waste (scrap metal), and requires numerous steps to obtain the final part geometry. As a more efficient alternative, powder metallurgical (PM) processes are now available to cost effectively fabricate both simple and complex shapes with minimal material waste. Combustion driven higher pressure powder compaction (CDC) for near-net or net shape manufacturing was recently developed. It offers a unique way of forming near-net or net shape high-density powder metal components both cost effectively and at relatively higher compaction pressures than other PM processes.

Shape memory alloy nanowires have been successfully produced from indium-thallium, one of the least-studied binary SMAs. This article provides a brief overview of the process and some of the unique properties of the material. The article is based on the winning entry in the 2012 International Metallographic Contest sponsored by the International Metallographic Society.

The use of coatings to enhance the performance of components is one of the most powerful tools in materials engineering. This article highlights some examples of how thermal spray technologies are used to enhance surface properties for selected applications and industries.

The article reviews National Transportation Safety Board (NTSB) investigations into multiple Cessna 210 aircraft accidents caused by failed hydraulic actuators in the main landing gear systems. Investigators discovered a pattern of fatigue cracks in 7075-T6 aluminum actuator barrels that initiated at corrosion pits along the retaining ring groove, propagated under cyclic loading, and eventually resulted in circumferential and longitudinal fractures that leaked hydraulic fluid. Although these failures have not yet caused significant injuries, they present serious safety risks by impairing pilots' ability to fully extend and lock the landing gear. The article details the metallurgical examinations that revealed multiple crack initiation sites containing chlorine-rich aluminum oxide pits, some with cadmium remnants from the adjacent steel retainer ring, suggesting potential corrosion mechanisms. The researchers conclude that the combination of thin-walled design, stress concentrations at the retaining ring groove, susceptibility of the high-strength aluminum alloy to corrosion, and possibly inadequate inspection procedures all contributed to these premature failures, prompting ongoing work with the FAA to address the issue.

Because the photopolymerization of gelatin methacrylate can be spatially and temporally controlled, it can be fabricated into hydrogels well suited to a variety of biomedical applications.