With the emergence of various new type molding technologies and the improvement of existing molding processes as well as the constant progress of material science, parts that have different textures have been produced and will enrich the production activity and life of human beings. Among them, the porous NiTi shape memory alloy that produced by metal injection molding technology is a kind of new alloy material that has superelasticity and good shape memory performance.
This kind of new alloy material has porous structure, which also has low density, high porosity and high permeability compared with many other dense materials. If we combine these performances with the excellent performances of traditional dense materials, it will increase a new possibility for new material development, especially it will inject new vitality to the development of composite material, intelligent material, biomedical material, silencing and damping material as well as other new materials that have strong functionality.
In the production of NiTi shape memory alloy by metal injection molding technology, the injection feeding that is mixed with nickel powder and titanium powder under the mass ratio of 10:2 as well as the paraffin base adhesive is used as the raw materials, in which the injection molding blank that has good uniformity will be generated under 400bar injection pressure and 328K mold temperature. After solvent degreasing, thermal debinding and self-propagating combustion, the sintered blank piece that has irregular hole shape but almost appear to be through-hole can be generated.
Compared with the shape memory alloy material that is made by compression moulding and other traditional powder metallurgy processes, this kind of metal injection molding shape memory alloy has larger aperture and porosity. Below are some introductions to the effect of this kind of memory alloy.
As shape memory alloy has special porous structure, it is often made into cold and hot fluid heating as well as cooling perforated tube driver. The temperature of this kind of driver will have an obvious cyclical change along with the change of time, which can meet the work demand of alternating driver. When using the alternating driver, the highest working temperature of the shape memory alloy will be higher than the ultimate temperature of austenite phase change, besides, the minimum fluctuant temperature will be lower than the ultimate temperature of martensite phase change.
In conclusion, due to the special porous structure of metal injection molding NiTi shape memory alloy, it will have obviously different physical and chemical property from the ordinary dense materials. Especially due to its excellent heat transfer and actuation property, it will have important application on the driver that requires high temperature variation. With the development of science technology, more similar new materials will be developed and will be widely used in broader field.
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