Sintering of
metallic powders
Most,
if not all, metals can be sintered. This applies especially to pure metals
produced in vacuum which suffer no surface contamination. Sintering under
atmospheric pressure requires the use of a protective gas, quite often endothermic gas.[4]Sintering, with subsequent reworking, can produce a
great range of material properties. Changes in density, alloying, or heat
treatments can alter the physical characteristics of various products. For
instance, the Young's Modulus En of sinterediron powders
remains insensitive to sintering time, alloying, or particle size in the
original powder, but depends upon the density of the final product:
Pasted
from <https://en.wikipedia.org/wiki/Sintering>
Plastics sintering
Plastic materials are formed by
sintering for applications that require materials of specific porosity.
Sintered plastic porous components are used in filtration and to control fluid
and gas flows. Sintered plastics are used in applications requiring wicking
properties, such as marking pen nibs. Sintered ultra high molecular weight polyethylene materials are used as ski and snowboard base materials. The porous texture
allows wax to be retained within the structure of the base material, thus
providing a more durable wax coating.
Hydrothermal synthesis includes the various techniques of crystallizing
substances from high-temperature aqueous solutionsat high vapor pressures
A
large number of compounds belonging to practically all classes have been
synthesized under hydrothermal conditions: elements, simple and complex oxides, tungstates, molybdates,
carbonates, silicates, germanates etc. Hydrothermal synthesis is commonly
used to grow synthetic quartz, gems and other
single crystals with commercial value. Some of the crystals that have been
efficiently grown are emeralds, rubies,
quartz, alexandrite and others. The method has proved to be
extremely efficient both in the search for new compounds with specific physical
properties and in the systematic physicochemical investigation of intricate
multicomponent systems at elevated temperatures and pressures.
No comments:
Post a Comment