• Uncategorized 28.11.2015

    Metal titanium and titanium alloys prepared by powder metallurgy method have large chemical activity, unconcerned to polluted by gas and furnace material, thus high quality titanium powder primarily in high vacuum or high purity inert gas protect, use spreading atomization process to produce. Products forming are generally nay adding binder, the blank must be sintered in vacuum. Late 1940s, it was the first to carry out the pressing and sintering technology research about sponge titanium powder as raw material. However, the product performance generated by this process can not meet the requirements of the aviation sector, mainly for the corrosion, filter and other parts of manufacturing chemical industry, light industry, metallurgy, marine development and other departments needed. Of which the first item won industrial application is titanium porous filter material.
    In mid-1960s, began to develop rotating electrode usage taking titanium alloy powder and hot isostatic densification process. Amidst this technology, the quiescent automatize properties of products are equivalent plus melting processing products, but considerably reduced machining, improved material utilization, started using for the piloting industry. To the late 1970s, titanium powder metallurgy products in corrosion resistance and aviation applications receive rapid development. In the early 1970s, Chinese metal powder supplier began the research of titanium powder metallurgy process and products, titanium valves, bushings, perforated tubes and plates, titanium-titanium carbide wear-resistant materials and corrosion resistant alloys such as titanium-molybdenum have industrial production. In the tarry 1970s, launched a research about efferent atomization fit high quality titanium pollen and hot isostatic pressing technology.
    Milling process to produce titanium and titanium alloy powders have the following four methods: ① sodium reduce sponge titanium powder. This pollen large yield, cheap, sprinkle plasticity is good, suitable for cold forming, is the major raw material to manifestation general corrosion products. Because of its high content sodium et alii chloride ions, it is easily to contaminated apparatus and rickety the materialize welding performance while sintering. ② electrolytic titanium powder. Soaring purity, but the moldability of the electrolytic titanium powder is poor than sponge titanium powder. ③ dehydrogenation hydrogenated titanium powder. Via hydrogenation dehydrogenation process can earn good quality, sheer grain size titanium powder and alloy powder; but the volume is small, the price is added expensive. ④ centrifugal atomization titanium powder. In 1960 U.S. was first use titanium curve rotating electrode method to prepare titanium pre-alloy powder, the powder is spherical. This alloy powder with high purity, uniformity composition, excellent fluidity, filling density is 65% of the theoretical value. Such powder should only use hot forming, tin use hot isostatic importunate summons made complex shape parts. Rotating electrode arc milling process, since there is a tungsten electrode rod, so it prone to produce tungsten contamination (tungsten-containing in dust is 400ppm), resolution reduce the enervation properties of materials. To eliminate tungsten contamination, it also developing an electron beam or plasma to heat the rotating electrode and arc rotating crucible and a variety of electron beam rotating disk centrifugal atomization process. This powder is the main raw material of manufacturing titanium powder metallurgy aviation components.

    Densification method depending on the powder materials’ requirements about the products, jug use different densification processes. Mainly have: ① bulk or low pressure forming powder sintered, sintered porosity is 25 to 70%. ② clamorous and sintering. Pressing tin be used mechanical oppositely isostatic pressing, pressing pressure at 2000 ~ 4000kgf/cm, the sintering temperature is 1000-1400℃. The grandchild density of the sintered body can be up to 92 to 95%. ③ thermoforming. Make the powder or powder billet pressure molding during the heating process. Excitable forming processes are mainly the hot isostatic pressing and vacuum hot pressing and so on. ④ the powder compact rolling of titanium powder and powder. These processes can obtain high density and good performance titanium powder materials or parts. Of which the powder undulating is the effective and prudent process of producing porous titanium and dense titanium.
    Source:http://www.mhcmp.com

    Posted by kid @ 3:33 pm

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