Application of memory alloy in mechanical and electronic products and biomedicine

Mechanical and electronic products

In 1970, the U.S. used shape memory alloy to make the low-temperature mating connector on the F-14 combat, and then there were more than millions of connector applications . Shape memory alloy is used in the hydraulic system of aircraft as a low temperature mating connection and in the small volume petroleum, petrochemical and electric industrial products. Another shape of the connector is a welded mesh wire, which is used to make a safety joint of the wire braid of the conductor. The connector has been used in sealing device, electrical connection device, electronic engineering mechanical device, and can work reliably at - 65 ~ 300 ℃. The developed sealing system device can be used as electrical connection in severe environment .

The shape memory alloy is made into a spring which can open and close the shutter to protect the fog lamp from flying debris. It is used for manufacturing precision instrument or precision lathe. Once it is deformed due to vibration, collision and other reasons, it can be eliminated by heating. In the process of mechanical manufacturing, all kinds of stamping and mechanical operation often need to transfer parts from one machine to another. Now, a kind of replacement manual or hydraulic clamp is developed by using shape memory alloy. This device is called driving cylinder, which has the characteristics of high efficiency, flexibility and large clamping force.

Biological medical treatment

In addition to its shape memory effect or hyperelasticity, TiNi shape memory alloy used in medical field should also meet the requirements of chemistry and biology, that is, good biocompatibility. TiNi can form stable passive film with organism. The main applications of TiNi Alloy in medicine are as follows:

(a) The tooth correction wire is made of super elastic TiNi alloy wire and stainless steel wire, and the super elastic TiNi alloy wire is the most suitable. Usually, stainless steel wire CoCr alloy wire is used for orthodontic treatment, but these materials have the disadvantages of high elastic modulus and small elastic strain. In order to give the appropriate correction force, the bow shape should be processed before correction, and the ligation and fixation should be skilled. If TiNi alloy is used as orthodontic wire, the plastic deformation will not occur even if the strain is up to 10%, and the stress-induced martensite makes the elastic modulus non-linear, that is to say, when the strain increases, the correction force fluctuates little. This material is not only easy to operate and has good curative effect, but also can reduce the discomfort of patients.

(b) Scoliosis correction of various scoliosis (congenital, habitual, neurological, rickets, idiopathic, etc.) diseases, not only physical and mental damage, but also the internal organs are oppressed, so it is necessary to carry out surgical correction. At present, this kind of operation adopts the stainless steel hadon rod orthopedic. When the orthopedic rod is placed in the operation, the orthopedic force on the fixed spine is required to be kept below 30-40kg. Once the force is too large, the orthopedic rod will be damaged. As a result, not only the spine, but also the nerve will be damaged. At the same time, the correction force will change with time after the appliance is placed. When the correction force drops to 30% of the initial value, surgery is needed to adjust the correction force again, which causes great pain to the patients both mentally and physically. The harrenton bar made of shape memory alloy only needs to be fixed once. If the correction force of the rod changes, enough correction force can be recovered by heating the shape memory alloy in vitro and raising the temperature to about 5 ℃ higher than the body temperature.

In addition, in surgery, TiNi shape memory alloy is used to make various bone connectors, vascular clips, coagulation filters and vasodilator elements. At the same time, it is widely used in stomatology, orthopedics, cardiovascular, thoracic surgery, hepatobiliary, Urology, gynecology and so on. With the development of shape memory, medical application will be more extensive.