Copper Niti Wires

Glasses memory alloy wire Temperature memory steel wire Imported nickel titanium alloy wire

Nitinol is a shape memory alloy. Shape memory alloy is a special alloy that can automatically restore its plastic deformation to its original shape at a certain temperature. Its expansion rate is more than 20%, its fatigue life is 1 * 10 to the 7th power, its damping characteristics are 10 times higher than ordinary springs, its corrosion resistance is better than the best medical stainless steel at present, so it can meet all kinds of engineering and Medical application needs are a very good functional material.

In addition to its unique shape memory function, memory alloys also have excellent characteristics such as wear resistance, corrosion resistance, high damping and super elasticity.

(1) Phase transformation and properties of nickel-titanium alloy

As the name implies, a nickel-titanium alloy is a binary alloy composed of nickel and titanium. Due to changes in temperature and mechanical pressure, there are two different crystal structure phases, namely an austenite phase and a martensite phase. The phase transformation sequence of the nickel-titanium alloy during cooling is the parent phase (austenite phase) -R phase-martensite phase. The R phase is rhombohedral, and austenite is a state when the temperature is higher (greater than the same: the temperature at which austenite starts), or when the load is removed (external force is removed from Deactivation). The shape is relatively stable. The martensite phase is the state when the temperature is relatively low (less than Mf: the temperature at which the martensite ends) or loaded (activated by external force), hexagonal, malleable, repeatable, less stable, and easier Deformed.

(2) Special properties of nickel-titanium alloy

1. Shape memory (shape memory) shape memory is when the mother phase of a certain shape is cooled from above the Af temperature to below the Mf temperature to form martensite, the martensite is deformed below the Mf temperature, and heated to below the Af temperature. With the reverse phase change, the material will automatically restore its shape in the parent phase. In fact, the shape memory effect is a heat-induced phase transformation process of nickel-titanium alloy.

2. Superelasticity The so-called superelasticity refers to the phenomenon that the sample produces a strain far greater than its elastic limit strain under the action of external force, and the strain can be automatically recovered when unloaded. That is, in the state of the parent phase, due to the effect of applied stress, the stress-induced martensite transformation occurs, so that the alloy exhibits a mechanical behavior different from that of ordinary materials. Its elastic limit is much greater than that of ordinary materials, and no longer observes Hu. Law. Compared with shape memory properties, superelasticity does not involve heat. In a word, superelasticity means that the stress does not increase with the increase of strain within a certain deformation range. Superelasticity can be divided into linear superelasticity and nonlinear superelasticity. The stress-strain curve in the former is close to a linear relationship between stress and strain. Non-linear superelasticity refers to the results of stress-induced martensitic transformation and its inverse phase transformation during loading and unloading in a certain temperature range above Af. Therefore, nonlinear hyperelasticity is also called phase transition pseudoelasticity. The pseudo-elasticity of the nickel-titanium alloy can reach about 8%. The superelasticity of the nickel-titanium alloy can change with the change of heat treatment conditions. When the archwire is heated above 400ºC, the superelasticity begins to decrease.

3. Sensitivity of temperature changes in the oral cavity: The curative power of stainless steel wire and CoCr alloy orthodontic wire is basically not affected by the temperature in the oral cavity. The orthodontic power of superelastic nickel-titanium alloy orthodontic wire changes with the change of oral temperature. When the amount of deformation is constant. As the temperature rises, the correction power increases. On the one hand, it can accelerate the movement of teeth, because the temperature changes in the oral cavity will stimulate the blood flow in the stagnation of blood flow caused by the correction device, so that the repair cells are fully nourished during the movement of the teeth. Maintain its vitality and normal function. On the other hand, orthodontists cannot accurately control or measure the correction power in the oral environment.

4. Corrosion resistance: Some studies have shown that the corrosion resistance of nickel-titanium wire is similar to that of stainless steel wire

5. Anti-toxicity: The special chemical composition of nickel-titanium shape memory alloy, that is, it is a kind of nickel-titanium and other atomic alloys, containing about 50% nickel, and nickel is known to have carcinogenic and cancer-promoting effects. In general, the titanium oxide on the surface layer acts as a barrier to make Ni-Ti alloys have good biocompatibility. TiXOy and TixNiOy of the surface layer can suppress the release of Ni.

6. Soft orthodontic power: The currently used orthodontic metal wires include austenitic stainless steel wire, cobalt-chromium-nickel alloy wire, nickel-chromium alloy wire, Australian alloy wire, gold alloy wire and ß titanium alloy wire. The load-displacement curve of these orthodontic correction wires under tensile test and three-point bending test conditions. Nitinol’s unloading curve platform is the lowest and flattest, indicating that it can provide long-lasting and gentle healing power.

7. Good shock absorption characteristics: the greater the shock to the archwire caused by chewing and nocturnal teeth, the greater the damage to the roots and periodontal tissues. Through the results of different arch wire attenuation experiments, it is found that the vibration amplitude of the stainless steel wire is larger than that of the superelastic nickel-titanium wire. The initial vibration amplitude of the superelastic nickel-titanium arch wire is only half that of the stainless steel wire. The good vibration and shock absorption characteristics of the arch wire The health of teeth is very important, and traditional arch wire, such as stainless steel wire, has a tendency to increase the absorption of tooth roots.

Application areas:

Used in super elastic memory alloy mobile phone antennas, fishing hooks, fishing rods, children’s toy antennas, optical glasses frames, Bluetooth headsets, ear hooks, and medical. With the development of the times, it is gradually used in the ladies’ clothing circle, which is used as scientific research materials and frequently appears in various laboratories of science and technology colleges.

2. Product features:

It has mechanical properties and corrosion resistance, and has a memory function, which can restore the memory shape at the phase transition temperature.

3. Product classification:

Two kinds of temperature memory and elastic memory.

4. Advantages:

With super memory, super elasticity, small size, light weight, small power, high strength, precise control, AC or DC activation, long life, linear motion.