geologia: Gadolinium

Evidence: 100 • authority: 72

Gadolinium is a chemical element; it has symbol Gd and atomic number 64. It is a silvery-white metal when oxidation is removed. Gadolinium is a ductile and malleable rare-earth element. It reacts with atmospheric oxygen or moisture slowly to form a black oxide coating. Gadolinium below its Curie point of 20 °C (68 °F) is ferromagnetic, with an attraction to a magnetic field higher than that of nickel. Above this temperature it is the most paramagnetic element. It is found in nature only in an oxidized form. When separated, it usually has impurities of the other rare earths because of their similar chemical properties. Gadolinium was discovered in 1880 by Jean Charles de Marignac, who detect…

Evidence: 53 • authority: 88

Effect of quenching temperature on microstructure and properties of multivariate high chromium cast iron. The effects of different quenching temperatures on the microstructure and properties of 3.3C-20.0Cr-1.0W-0.5B-2.0V-1.8Mo (wt.%) high-chromium cast iron were investigated using an optical microscope, scanning electron microscope, X-ray diffractometer, Rockwell hardness tester, microhardness tester, and wear testing machine. The results show that the microstructure of as-cast multivariate high chromium cast iron mainly consists of eutectic carbides (M 7 C 3 ), austenite and martensite matrix. In the process of quenching temperature increasing from 950 °C to 1150 °C, the morphology of mass…

Evidence: 42 • authority: 80

On a tantalum and silicon strengthened chromiumiron alloy part 1 — Metallurgical properties

Evidence: 29 • authority: 88

FACTORS INFLUENCING THE MECHANICAL PROPERTIES OF HIGH CHROMIUM WHITE CAST IRON. The high chromium white cast iron (HCWCI) has been in use for decades and is expected to remain popular due to its superb wear resistance. This wear resistant material is recognized for its superior hardness, toughness, and corrosion resistance. It is widely used in industries such as mining, cement, and power generation, where high abrasion and impact resistance are essential. The studies in this paper were conducted on an alloy containing 24.48% chromium, 2.66% carbon 1.32% molybdenum, 1.6% nickel, 0.99% silicon and 0.96% manganese. Mechanical and microstructural characterization was carried out on both as-cas…

Evidence: 24 • authority: 72

Iron is a chemical element; it has symbol Fe (from Latin ferrum) and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's outer and inner core. It is the fourth most abundant element in the Earth's crust. In its metallic state it was mainly deposited by meteorites. Extracting usable metal from iron ores requires kilns or furnaces capable of reaching 1,500 °C (2,730 °F), about 500 °C (900 °F) higher than that required to smelt copper. Humans started to master that process in Eurasia during the 2nd millennium BC and the use of iron tools and weapons began to disp…

Evidence: 24 • authority: 72

Chromium is a chemical element; it has symbol Cr and atomic number 24. It is the first element in group 6. It is a steely-grey, lustrous, hard, and brittle transition metal. Chromium is valued for its high corrosion resistance and hardness. A major development in steel production was the discovery that steel could be made highly resistant to corrosion and discoloration by adding metallic chromium to form stainless steel. Stainless steel and chrome plating (electroplating with chromium) together comprise 85% of the commercial use. Chromium is also greatly valued as a metal that is able to be highly polished while resisting tarnishing. Polished chromium reflects almost 70% of the visible spec…