The present invention refers to a gray cast iron alloy with chemical composition especially developed to promote high hot mechanical strength and good thermal conductivity, with antimony and nitrogen contents, wherein the antimony content ranges from 0.05 to 0, 12% by weight, and the nitrogen content ranges from 0.008 to 0.013% by weight, based on the total weight of the gray cast iron alloy.

The present invention refers to a gray cast iron alloy with chemical composition especially developed to promote high hot mechanical strength and good thermal conductivity, with antimony and nitrogen contents, wherein the antimony content ranges from 0.05 to 0, 12% by weight, and the nitrogen content ranges from 0.008 to 0.013% by weight, based on the total weight of the gray cast iron alloy.

A powder metal composition for high wear and temperature applications is made by atomizing a melted iron based alloy including 3.0 to 7.0 wt. % carbon; 10.0 to 25.0 wt. % chromium; 1.0 to 5.0 wt. % tungsten; 3.5 to 7.0 wt. % vanadium; 1.0 to 5.0 wt. % molybdenum; not greater than 0.5 wt. % oxygen; and at least 40.0 wt. % iron. The high carbon content reduces the solubility of oxygen in the melt and thus lowers the oxygen content to a level below which would cause the carbide-forming elements to oxidize during atomization. The powder metal composition includes metal carbides in an amount of at least 15 vol. %. The microhardness of the powder metal composition increases with increasing amounts of carbon and is typically about 800 to 1,500 Hv50.

A powder metal composition for high wear and temperature applications is made by atomizing a melted iron based alloy including 3.0 to 7.0 wt. % carbon; 10.0 to 25.0 wt. % chromium; 1.0 to 5.0 wt. % tungsten; 3.5 to 7.0 wt. % vanadium; 1.0 to 5.0 wt. % molybdenum; not greater than 0.5 wt. % oxygen; and at least 40.0 wt. % iron. The high carbon content reduces the solubility of oxygen in the melt and thus lowers the oxygen content to a level below which would cause the carbide-forming elements to oxidize during atomization. The powder metal composition includes metal carbides in an amount of at least 15 vol. %. The microhardness of the powder metal composition increases with increasing amounts of carbon and is typically about 800 to 1,500 Hv50.

The present disclosure discloses a high-strength and high-thermal conductivity new material composite brake drum and a preparation method thereof. The composite brake drum is composed of an outer layer of high-strength ductile iron and an inner layer of high-thermal conductivity gray cast iron, which are integrated by centrifugal compound casting. The outer layer of the composite brake drum is firstly poured on the production line of iron particle-filled coated sand shells. Due to the fast solidification and cooling of the iron particle-filled coated sand shells, the castings have the characteristics of fine and dense organization structures to ensure the high strength and high toughness of the ductile iron of the outer layer. On this basis, the inner gray cast iron is poured under centrifugal casting conditions, in which a good metallurgical bond between the inner and outer layers is achieved by controlling the centrifugal casting process.

The present disclosure discloses a high-strength and high-thermal conductivity new material composite brake drum and a preparation method thereof. The composite brake drum is composed of an outer layer of high-strength ductile iron and an inner layer of high-thermal conductivity gray cast iron, which are integrated by centrifugal compound casting. The outer layer of the composite brake drum is firstly poured on the production line of iron particle-filled coated sand shells. Due to the fast solidification and cooling of the iron particle-filled coated sand shells, the castings have the characteristics of fine and dense organization structures to ensure the high strength and high toughness of the ductile iron of the outer layer. On this basis, the inner gray cast iron is poured under centrifugal casting conditions, in which a good metallurgical bond between the inner and outer layers is achieved by controlling the centrifugal casting process.

A spheroidal graphite cast iron having an excellent impact strength at low temperature and a method for producing the same are provided. The present disclosure relates to the spheroidal graphite cast iron comprising: C: 3.5 mass % to 4.2 mass %; Si: 2.0 mass % to 2.8 mass %; Mn: 0.2 mass % to 0.4 mass %; Cu: 0.1 mass % to 0.7 mass %; Mg: 0.02 mass % to 0.06 mass %; Cr: 0.01 mass % to 0.15 mass %; and the balance: Fe and inevitable impurities, wherein Mn+Cr+Cu is 0.431 mass % to 1.090 mass %, a graphite nodule count is 230/mm.sup.2 or less, and a pearlite fraction is 30% to 85%.

A spheroidal graphite cast iron having an excellent impact strength at low temperature and a method for producing the same are provided. The present disclosure relates to the spheroidal graphite cast iron comprising: C: 3.5 mass % to 4.2 mass %; Si: 2.0 mass % to 2.8 mass %; Mn: 0.2 mass % to 0.4 mass %; Cu: 0.1 mass % to 0.7 mass %; Mg: 0.02 mass % to 0.06 mass %; Cr: 0.01 mass % to 0.15 mass %; and the balance: Fe and inevitable impurities, wherein Mn+Cr+Cu is 0.431 mass % to 1.090 mass %, a graphite nodule count is 230/mm.sup.2 or less, and a pearlite fraction is 30% to 85%.

In a method for recovering a copper sulfide concentrate by froth flotation from an ore containing an iron sulfide, wet grinding of the ore with grinding media made of high chromium cast iron alloy having a chromium content of from 10 to 35% by weight is combined with an addition of hydrogen peroxide to the conditioned mineral pulp before or during flotation in order to improve concentrate grade and recovery of copper sulfides.

In a method for recovering a copper sulfide concentrate by froth flotation from an ore containing an iron sulfide, wet grinding of the ore with grinding media made of high chromium cast iron alloy having a chromium content of from 10 to 35% by weight is combined with an addition of hydrogen peroxide to the conditioned mineral pulp before or during flotation in order to improve concentrate grade and recovery of copper sulfides.