| Sažetak | S rastom i razvojem raznih industrijskih grana, kao što su kemijska, zrakoplovna i svemirska, raste i potražnja za metalima sa posebnim svojstvima. Jedna od skupina tih metala su metali visokog tališta ili vatrostalni metali, a u nju spadaju niobij, tantal, molibden, volfram i renij. Osim visoke temperature tališta, kao što im i samo ime govori, metali visokog tališta odlikuju se visokom gustoćom, čvrstoćom i tvrdoćom, te otpornošću na koroziju i trošenje. Radi tih svojstava koriste se za izradu dijelova poput elemenata mlaznog motora, toplinskih štitova, grijaćih elemenata, spremnika za kiseline, opruga, kondenzatora, reznih alata i drugih.
Iako su otkriveni ranije, njihova uporaba kreće tek u 20. stoljeću razvojem metalurgije praha metodama kao što su hladno i vruće prešanje, te hladno i vruće izostatsko prešanje.
U ovome radu će se opisati metode njihovog dobivanja i prerada iz mineralnih ruda, tehnološki postupci obrade te svojstva i područja primjene čistih metala kao i njihovih legura. |
| Sažetak (engleski) | With the growth and development of many industries, such as chemical, aeronautical and space industries, the need for metals with special properties also grows. One group of those metals are the refractory metals, which includes niobium, tantalum, molybdenum, tungsten and rhenium. Beside the high melting point, as their name suggests, these metals are known for their high density, strength and hardness and their resistance to corrosion and wear. Because of these properties, they are used for making items such as jet engines, heat shields, heating elements, acid vats, springs, capacitors, cutting tools and others.
Although they were discovered earlier, their use doesn't begin until 20. century with the development of powder metallurgy technologies such as cold and warm pressing and cold and warm isostatic pressing.
This thesis will describe the methods of obtaining and refining refractory metal ores, their processing technologies, including the properties and areas of application for pure metals as well as their alloys. |
