There is, I think, something ethereal about i —the square root of minus one. I remember first hearing about it at school. It seemed an odd beast at that time—an intruder hovering on the edge of reality.

Usually familiarity dulls this sense of the bizarre, but in the case of i it was the reverse: over the years the sense of its surreal nature intensified. It seemed that it was impossible to write mathematics that described the real world in …

I and i

다중혈관 관상동맥 환자에서 y-문합을 이용하여 양쪽 내흉동맥만을 사용한 우회술의 조기 성적

Elemental Mg and Mg-alloy (AZ91D) based composites reinforced with 15 vol.% silicon carbide (SiC) particulates (average particle size 15 μm and 150 μm) were synthesised by stir casting technique. Particle distribution, particle–matrix interfacial reaction, hardness and mechanical properties in the as cast as well as T4 heat-treated conditions were investigated. The composite materials show uniform distribution of SiC particulates. The average grain size decreases with the presence of SiC particulates and the grain size further decreases as the particle size decreases. The AZ91D alloy composite shows an increase in hardness and elastic modulus compared to monolithic alloys. The improvement in elastic modulus of composite containing 15 μm size SiC particles is significantly higher than the composite with 150 μm size particles. The ultimate tensile strength and ductility of composite materials were reduced compared to unreinforced alloy.

Processing and mechanical properties of SiC reinforced cast magnesium matrix composites by stir casting process

Wear characteristics of surface-hybrid-MMCs layer fabricated on aluminum plate by friction stir processing

Tribological properties of powder metallurgy – Processed aluminium self lubricating hybrid composites with SiC additions

Analyzing the mechanisms of fatigue crack initiation and propagation in CRH EMU brake discs

The effect of braking energy on the fatigue crack propagation in railway brake discs

https://epublications.marquette.edu/cgi/viewcontent.cgi?article=1245&context=mechengin_fac

Crack propagation and microstructural transformation on the friction surface of a high-speed railway brake disc

A vacuum stir casting process is developed to produce SiCp reinforced cast magnesium matrix composites. This process can eliminate the entrapment of external gas onto melt and oxidation of magnesium during stirring synthesis. Two composites with Mg-Al9Zn and Mg-Zn5Zr alloys as matrices and 15 vol.% SiC particles as reinforcement are obtained. The microstructure and mechanical properties of the composites and the unreinforced alloys in as-cast and heat treatment conditions are analyzed and evaluated. In 15 vol.% SiCp reinforced Mg-Al9Zn alloy-based composite (Mg-Al9Zn/15SiCp), SiC particles distribute homogenously in the matrix and are well bonded with magnesium. In 15 vol.% SiCp reinforced Mg-Zn5Zr alloy-based composite (Mg-Zn5Zr/15SiCp), some agglomerations of SiC particles can be seen in the microstructure. In the same stirring process conditions, SiC reinforcement is more easily wetted by magnesium in the Mg-Al9Zn melt than in the Mg-Zn5Zr melt. The significant improvement in yield strength and elastic modulus for two composites has been achieved, especially for the Mg-Al9Zn/15SiCp composite in which yield strength and elastic modulus increase 112 and 33%, respectively, over the unreinforced alloy, and increase 24 and 21%, respectively, for the Mg-Zn5Zr/15SiCp composite. The strain-hardening behaviors of the two composites and their matrix alloys were analyzed based on the microstructure characteristics of the materials.

Jianmin Han

Papers

Analyzing the mechanisms of fatigue crack initiation and propagation in CRH EMU brake discs

The effect of braking energy on the fatigue crack propagation in railway brake discs

Crack propagation and microstructural transformation on the friction surface of a high-speed railway brake disc

Fabrication and characterization of cast magnesium matrix composites by vacuum stir casting process

Low cycle fatigue behavior of Cr–Mo–V low alloy steel used for railway brake discs