Explanation: Pulverization is a process of preparation of powders for metallurgical operations. It can be done using a variety of machines like hammering, counter-rotating plates, or ball milling. Depending on the type of metal and the grain size, an appropriate pulverization technique can be chosen.

Explanation: This process is mostly similar to pulverization but requires special nozzles at controlled temperature and pressure. It has a disadvantage of oxidation of molten metal when in contact with air.

Explanation: Since atomization results in oxidation of molten metal as it comes in contact with air, it is only used for materials like zinc and cadmium. Electrolysis is a standard electrolytic process which is used for materials like silver and tin. It is advantageous as it produces oxidation resistant powders.

Explanation: In gravity compaction, the die is filled with loose powder which is then sintered. The die is usually made of an inert material such as graphite. Since pressure is not used, the parts are more porous.

Explanation: The sintering process is usually carried out at a temperature below the highest melting constituent. In some cases, the temperature is high enough to form a liquid constituent. In other cases, no melting of any constituent takes place.

Explanation: In the production of cemented carbide cutting tools, a mixture of carbides of tungsten, tantalum, and titanium with cobalt as a binder is compacted and pre-sintered. These can be cut, machined, and ground into the final shape. The compact is then subjected to a high-temperature sintering operation at 2750 F.

Explanation: The sintered part is repressed in the die to reduce the void space and impart the required density. This is known as coining. Sizing operation improves the surface finish of the component at the cost of change in density.

Explanation: Sintered parts may be impregnated with oil, grease, wax, or other lubrication materials. The parts are immersed in the lubricant and heated to about 93oC. The porous structure gets completely impregnated in 10-20 minutes.

Explanation: The oldest method of pig casting in sand beds was superseded by pig casting machines. Machine cast pigs are cleaner than sand cast pigs and have no adhering sand to contaminate the remelt process. The size of the pig (iron) for foundry is about 20*9*4 inches in size.

Explanation: Pig iron is the raw material for all iron and steel products. It is composed of 3-4% carbon, 1-3% silicon, 0.3-0.7% phosphorus, 0.1-1.0% manganese, and less than 1% sulfur. The remaining composition is that of iron.

Explanation: Basic pig iron must be low in sulfur of about 0.04%. This is since sulfur is an active impurity in steels and is not eliminated in refining furnaces.

Explanation: Ferromanganese and ferrosilicon are two ferroalloys of pig iron, which are used as additives. Ferromanganese contains about 74-82% manganese, whereas ferrosilicon contains 5-17% silicon.

Explanation: The Bosh is the smelting zone and the hottest part of the furnace. It extends upwards from the tuyere level and has an outward slope of 20 degrees with a height of about 3.6 meters.

Explanation: The iron ore processed in blast furnaces is usually in the form of an oxide. This is either hematite or magnetite. Hematite contains 50-65% iron and is used in a greater proportion than magnetite. The ore pieces are usually less than 100 mm in diameter.

Explanation: Fluxes must form slags of low viscosity and low density so that the slag will settle freely down through the charge and float in a distinct layer of iron in the hearth. Limestone or dolomite usually acts are the flux in iron smelting. The slag also helps in control of chemical properties of iron.