Effects of Pre- and Post-Carburizing Surface Modification on the Tribological and Adhesion Properties of Heat-Resistant KHR 45A Steel for Cracking Tubes.

In this study, the effects of ultrasonic nanocrystal surface modification (UNSM) technology on the tribological properties and scratch-induced adhesion behavior of a heat-resistant KHR 45A steel cracking tube, which is used for the pyrolysis process, were investigated. The main objective of this study is to investigate the effects of pre- and post-carburizing UNSM treatment on the tribological and adhesion performances of carburized domestic KHR 45A (A) steel and to compare the results with the existing carburized Kubota-made KHR 45A steel (B). A carburizing process was carried out on the polished and UNSM-treated KHR 45A steel substrates, which were cut out from the cracking tube, at 300 °C heat exposure for 300 h.

Mechanical and Tribological Characteristics of Cladded AISI 1045 Carbon Steel.

This study introduces a newly developed cladding device, through printing AISI 1045 carbon steel as single and double layers onto American Society for Testing and Materials (ASTM) H13 tool steel plate. In this study, the mechanical and tribological characteristics of single and double layers were experimentally investigated. Both layers were polished first and then subjected to ultrasonic nanocrystal surface modification (UNSM) treatment to improve the mechanical and tribological characteristics.

Bearings Downsizing by Strength Enhancement and Service Life Extension.

Slim bearings are used widely in aircrafts, robots, wind turbines, and industrial machineries, where their size and weight are very important for the performance of a system. The common materials of slim bearings for robots and industrial machineries are based on SAE52110 bearing steel, and special heat treatment and a super polishing process are used and adapted to improve the rolling contact fatigue (RCF) strength of bearings. The improvement in RCF strength, depending on contact stress, surface hardness, and the friction behavior before and after ultrasonic nanocrystalline surface modification (UNSM) treatment was validated.

Friction and Wear Reduction of Eccentric Journal Bearing Made of Sn-Based Babbitt for Ore Cone Crusher.

An anti-friction Babbitt alloy-coated bearing made by a casting process is a journal bearing, which is used in an ore cone crusher eccentric. The main purpose of the Babbitt coated eccentric is to provide a low friction to support and guide a rotating shaft. Despite the fact that the Babbitt-coated eccentric offers a low friction coefficient and can be operated without a continuous supply of lubricant, it suffers from mining environments and short service life.

Wear Enhancement of Wheel-Rail Interaction by Ultrasonic Nanocrystalline Surface Modification Technique.

In this study, an ultrasonic nanocrystalline surface modification (UNSM) technique was applied to normal and heat-treated rails made of 60 kgK steel to enhance the wear resistance of the wheel-rail interaction. The hardness and compressive residual stress values of the untreated and UNSM-treated rails were measured by the Brinell hardness tester and X-ray diffraction technique, respectively. It was found, according to the measurement results, that the hardness was increased by about 20% and 8%, whereas the compressive residual stress was induced by about 52% and 62% for the UNSM-treated normal and heat-treated rails, respectively.

Low friction and high strength of 316L stainless steel tubing for biomedical applications.

We propose herein a nondestructive surface modification technique called ultrasonic nanocrystalline surface modification (UNSM) to increase the strength and to improve the tribological performance of 316L stainless steel (SS) tubing. Nanocrystallization along nearly the complete tube thickness of 200μm was achieved by UNSM technique that was confirmed by electron backscatter diffraction (EBSD). Nano-hardness of the untreated and UNSM-treated specimens was measured using a nanoindentation.

Mechanical and fatigue characteristics of Ti-6Al-4V extra low interstitial and solution-treated and annealed alloys after ultrasonic nanocrystal surface modification treatment.

This study investigates the influence of ultrasonic nanocrystal surface modification (UNSM), a novel surface treatment technology, on the mechanical characteristics and rotary bending fatigue performance of solution-treated and annealed (STA) Ti-6Al-4V and Ti-6AI-4V extra low interstitial (ELI) alloys. Various techniques have been developed to use surface modification in order to improve fatigue performance of machine parts. The UNSM treatment emerges due to its ability to induce a distinctive combination of modifications in the top surface and the subsurface of the material.

Restoration of rolling-contact-fatigued surfaces via nanoskin technology.

Rolling contact fatigue (RCF) is known as the dominant factor determining the service life of bearing materials. In this work, the fatigue life of the typical bearing alloy was significantly improved by introducing a nanoskin layer on the surfaces of the test specimens. The nanoskin layer structure was obtained by means of the ultrasonic nanocrystal surface modification (UNSM) technology.

Fatigue characteristics of SAE52100 steel via ultrasonic nanocrystal surface modification technology.

Ultrasonic nanocrystal surface modification (UNSM) technology is a novel surface modification technology that can improve the mechanical and tribological properties of interacting surfaces in relative motion. UNSM treatment was utilized to improve the wear resistance fatigue strength of slim bearing rings made of SAE52100 bearing steel without damaging the raceway surfaces. In this study, wear and fatigue results that were subjected to different impact loads of the UNSM treatment were investigated and compared with those of the untreated specimen.

Infestation status of Paragonimus westermani metacercariae in the second intermediate host in Ulchin county, Kyungpook Province.

A study on the population density of crayfish intermediate hosts and infestation status of crayfish with encysted larvae of Paragonimus westermani in Ulchin county, Kyungpook province, Korea was conducted from May to October in 1986. The population density of the crayfish ranged from 1 to 13, with an average of 4 per manhour. Among the six habitats, Ducheon had a somewhat higher density than that of the others.