How Is Nitinol Manufactured?

How is Nitinol manufactured? Virtually all Nitinol components go through a similar series of basic manufacturing steps. To produce the basic material forms, such as wire, tubing, ribbon, sheet and bar, Nitinol materials are vacuum-melted, hot-worked, cold-worked and then heat-treated to achieve final properties.

What elements make up Nitinol?

Nitinol is a nickel-titanium alloy with the typical ratio 40-50% nickel, 50-60% titanium known as a shape memory alloy (SMA), a metal alloy that demonstrates pseudo-elasticity and the shape memory effect.

Where did Nitinol come from?

The term nitinol comes from its composition and where it was discovered: nickel titanium/naval ordnance laboratory. In 1959, two scientists were exploring the properties of metal alloys.

Is Nitinol environmentally friendly?

Nitinol engines have been demonstrated to run continuously for over a year with no degradation and have very little impact on the environment throughout their life-cycle, making them a truly green energy source.

How does Nitinol wire work?

In robotics, Nitinol can be used as an actuator where an electrical current (or heat) is applied to a stretched wire, and the wire will contract while the charge is applied and relax once the charge is removed. Unlike most metals, Nitinol contracts in length when heated but will maintain the same absolute volume.

Related guide for How Is Nitinol Manufactured?

Are paper clips made of Nitinol?

This paper clip is made from a nickel-titanium alloy (NITI/Nitinol) wire, which can have two distinct types of internal crystal structures. When heated above its actuation temperature the wire will transform to the other crystal structure and the wire will spring back to its "remembered" shape.

Why is Nitinol made under vacuum?

Vacuum Arc Remelting: In this method, an electrical arc is struck between a water cooled copper strike-plate and the raw materials. Water cooled copper mold is used for melting the constituents in high vacuum to prevent carbon introduction.

Can you machine Nitinol?

Nitinol is known as a difficult-to-machine alloy due to its high hardness, which requires a large amount of cutting force, resulting in high rate of tool wearing. Therefore, researchers have made an effort to ameliorate the machinability of this material to achieve a finer surface quality.

What kind of metal is Nitinol?

Nitinol was developed by the U.S. Navy and stands for nickel titanium alloy. This metal is particularly useful for medical applications because it has thermal memory. This property allows stents to be made at a certain diameter, cooled, and then compressed onto a delivery system.

How is Nitinol wire formed?

Who makes Nitinol?

Nitinol was developed by the Naval Ordnance Laboratory. The name comes from its composition and the discovery team who first recognized the potential of this powerful alloy (NIckel/TItanium/Naval Ordinance Laboratory). Nitinol alloys are typically made of 55%-56% Nickel and 44%-45% Titanium.

Why was Nitinol invented?

Nitinol was discovered [9] in 1959 by Buehler W.J. of the Naval Ordinance Laboratory while trying to develop an impact-, fatigue-and heat-resistant alloy to use as the nose cone of a navy missile.

Does Nitinol corrode?

The corrosion stability of Nitinol is strongly dependent on the surface preparation—grinding, polishing or chemical etching. Whereas a ground surface is not resistant to localized corrosion, polished and chemically etched surfaces are resistant to this type of corrosion attack.

Why is Nitinol called a smart alloy?

'A shape-memory alloy (SMA, smart metal, memory metal, memory alloy, muscle wire, smart alloy) is an alloy that "remembers" its original shape and that when deformed returns to its pre-deformed shape when heated. ' Nitinol (or SMA wire) is made up of nickel and titanium.

Is Nitinol a compound or mixture?

However, as Nitinol is an intermetallic compound and not an alloy in the metallurgical sense, the bonding force of Nickel to Titanium is much stronger than to the alloy components in stainless steel.

Is Nitinol hard making?

Nitinol is difficult to weld, both to itself and other materials. Laser welding nitinol to itself is a relatively routine process. More recently, strong joints between NiTi wires and stainless steel wires have been made using nickel filler.

What is martensite and austenite phase?

Nitinol typically exhibits two phases: austenite and martensite. Austenite has a body center cubic structure and is stable at higher temperatures. Martensite is a monoclinic crystal which is stable at lower temperatures (Fischer et al., 2002).

What is the elastic modulus of Nitinol?

Nitinol mechanical properties

Young's modulus**** austenite approx. 83 GPa (12E6 psi)
martensite approx. 28 to 41 GPa (4E6 to 6E6 psi)
Yield strength austenite 195 to 690 MPa (28 to 100 ksi)
martensite 70 to 140 MPa (10 to 20 ksi)
Ultimate tensile strength fully annealed 895 MPa (130 ksi)

What happens if you put a paperclip in vinegar?

When a similar thing happens to iron you can see it as rust. The acid in the vinegar dissolves the copper oxide to leave you with a bright shiny penny! of copper on the paperclip. Your paperclip might not be completely covered, but it will have enough copper on it to see!

What happens when you put a paperclip in vinegar?

In this reaction, copper atoms from the pennies replace iron atoms in the paperclips. First, the copper atoms dissolve in the vinegar salt solution. Then they travel through the solution to the paperclip. The copper becomes solid on the paperclip, and the iron dissolves into the vinegar and salt solution.

What is the composition of a paperclip?

A paper clip (paperclip) is a device used to hold sheets of paper together, usually made of steel wire bent to a looped shape (though some are covered in plastic).

Are braces made of Nitinol?

Nitinol is a metal alloy – or mixture – of nickel and titanium. This type of wire is also known as “memory wire” or “smart wire,” and it can be used as one of the parts of braces.

Is Nitinol stronger than titanium?

Compared with the titanium nail, the Nitinol nail developed a lower contact force between the nail and canal; consequently the Nitinol nail's ultimate force was also lower. The stainless steel nail provided higher structural stiffness than did the titanium nail in Kaiser's study [30].

How does a Nitinol engine work?

The Nitinol exerts torque on the lower (smaller) wheel as it tries (in vein) to return to its original shape. This torque spins the lower wheel, and more Nitinol is drawn into the hot water. The other side of the loop is cooled by the air which momentarily relaxes the wire as it passes around the smaller pulley.

How hot should Nitinol get?

The transition temperature varies depending upon the exact composition of the Nitinol alloy. Nitinol comes in many activation temperatures from 30°C (86°F) to 130°C (266°F).

What do you have to do to set a new shape for Nitinol?

In general, temperatures as low as 400 deg. C and times as short as 1-2 minutes can set the shape, but generally one uses a temperature closer to 500 deg. C and times over 5 minutes. Rapid cooling of some form is preferred via a water quench or rapid air cool (if both the parts and the fixture are small).

How is Nitinol used in the medical field?

It is now widely used for many medical components, including reinforcement braiding and coiling for catheter tubing and shafts, braided and formed stents, formed retrieval baskets, and many other applications.

Are people allergic to nitinol?

Nitinol allergy is a rare phenomenon, with few reported cases in the literature. However, allergy to nickel, a predominant component of nitinol, is much more common. Despite the prevalence of nickel allergy few patients present with clinical manifestations.

Are there different types of nitinol?

There are two primary types of Nitinol: superelastic and shape memory, which are determined by transformation temperature. Superelastic Nitinol is cooler, and shape memory Nitinol is warmer.

How are shape memory polymers made?

Shape memory polymers are polymer materials that you can deform and then by applying a stimulus, such as heat or light, will return to its previous shape. So far this has been achieved using heat, light, irradiation with infrared light, immersion in water, and application of electric or magnetic fields.

How strong is nitinol?

At room temperature, nitinol has an ultimate tensile strength of between 103 and 1,100 MPa. By way of comparison, steel possesses a tensile strength of between 300 and 2,400 MPa, depending upon the material's composition.

How does shape memory for nitinol work?

When a shape memory alloy is in its martensitic form, it is easily deformed to a new shape. However, when the alloy is heated through its transformation temperatures, it reverts to austenite and recovers its previous shape with great force. This process is known as shape memory.

What is special about Nitinol?

Nitinol is a metal alloy of nickel and titanium with unique properties, including superelasticity or pseudoelasticity and “shape memory” properties. That means nitinol can remember its original shape and return to it when heated. It also shows great elasticity under stress.

Is nitinol toxic?

We conclude that Nitinol has good in vitro biocompatibility with human osteoblasts and fibroblasts. Despite the higher initial nickel dissolution, Nitinol induced no toxic effects, decrease in cell proliferation, or inhibition on the growth of cells in contact with the metal surface.

Why is Nitinol used for stents?

First-generation Nitinol stents were designed to provide sufficient scaffolding forces to hold open vessels, yet provide enough elasticity to "breathe" with pulsatile pressure differentials from the cardiac cycle. A variety of clinical studies indicate that these stents perform this primary function quite well.

What are some properties of Nitinol that make it so biocompatible for medical use?

In medical devices, Nitinol is popular due to its biocompatibility, superelasticity and fatigue and kink resistance (5). Nitinol is used to manufacture catheter tubes, guidewires, stone retrieval baskets, filters, needles, dental files and archwires and other surgical instruments (6).

How much does Nitinol cost?

The device comes in several sizes and costs between $15 and $40. This week the company announced the latest version of the device, which will allow the flow of hot water to resume automatically as the water from the shower head starts to cool. Orthodontists are now using nitinol on the wires and springs in braces.

Is Nitinol a light?

Oxide surface—Current Nitinol producers make Nitinol with an oxide surface that varies in color from light amber to blue to a black color.

Does Nitinol oxidize?

These superficial cracks expose Ni-rich phases that grow during the oxidation of Nitinol. Above 10µm, however, the oxide forms a protective insulating barrier and the breakdown potential increases to 1000mV.

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