ホームページ
記事
The Basics of Nonferrous Metallurgy

The Basics of Nonferrous Metallurgy

142 記事

Platinum and Its Use

Platinum, a rare and valuable precious metal, plays a crucial role in modern industry and technology. This comprehensive article explores platinum's physical properties, chemical characteristics, and diverse applications across multiple sectors. From its vital role in automotive catalytic converters to its use in jewelry and electronics, platinum's unique properties make it indispensable in contemporary manufacturing.

Precious Metals

This comprehensive article examines precious metals, including silver, gold, and the platinum group (platinum, palladium, ruthenium, rhodium, osmium, and iridium). It details their unique physical and chemical properties, such as high density, corrosion resistance, electrical conductivity, and light reflectivity. The text explores measurement systems for purity, including fineness and karats, while highlighting industrial applications across electronics, jewelry, automotive, aerospace, and chemical sectors.

Precipitation Hardening of Aluminum Alloys

Precipitation hardening, or age hardening, provides one of the most widely used mechanisms for the strengthening of metal alloys. The strongest aluminum alloys (2xxx, 6xxx and 7xxx) are produced by age hardening.
In order for an alloy system to be able to be precipitation-strengthened, there must be a terminal solid solution that has a decreasing solid solubility as the temperature decreases. The precipitation-hardening process involves three basic steps: solution treatment, quenching and aging.

Rapidly Solidified Aluminum Alloys

Among the specific contributions and potentials of rapid solidifications are: increased solid solubility, minimization of segregation, highly refined grain size, modification or elimination of segregation phases, possibility of glass formation and production of new metastable microcrystalline structures.
Corresponding improvements have been achieved in mechanical, corrosive, magnetic and other properties, higher ultimate tensile (UTS) and yield strengths, with better elongations, better pitting and general corrosive behavior due to ultrafine grain sizes, decreased segregation and refinement of phases, increased fatigue life, higher strength-to-weight ratios and many others.

Recycling Aluminum Alloys

The aluminum recycling industry faces new challenges due to shifting consumption patterns: increased use in transportation, declining beverage can recycling rates, and the fabrication industry's growing dependence on secondary aluminum. These trends necessitate innovative approaches to material design and processing.

Refractory Metals: Niobium, Molybdenum and Rhenium

The refractory metals include niobium (also known as columbium), tantalum, molybdenum, tungsten, and rhenium. With the exception of two of the platinum-group metals, osmium and iridium, they have the highest melting temperatures and lowest vapor pressures of all metals.
The refractory metals are readily degraded by oxidizing environments at moderately low temperatures, a property that restricted the applicability of the metals in low-temperature or nonoxidizing high-temperature environments. Protective coating systems have been developed, mostly for niobium alloys, to permit their use in high-temperature oxidizing aerospace applications.