NAKAYAMA STEEL WORKS, LTD. Amorphous Development

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NAKAYAMA STEEL WORKS, LTD. / Amorphous Development

Since 2004, Nakayama Steel Works, Ltd., a medium-sized steel manufacturing company, has been developing technology for coating materials with amorphous metals using the original coating device we invented. Our latest technological development introduced here consists of the following two fundamental technologies.

（1）	Development of chemical components of amorphous metal with the highest resistance to corrosion and abrasion
	The Fe-35Cr amorphous metal we developed this time has the world’s highest resistance to corrosion. For example, the Fe-35Cr amorphous metal corrodes by only 0.002 mm in aqua regia after one year, which is the most corrosive reagent, at 25℃.

（2）	World’s first small metal-coating device
	We have developed a device for coating parts (e.g., shafts) with amorphous metals. This device can coat the surface of a part with amorphous metals by melting the Fe-35Cr amorphous metal described at 2600℃ and then cooling it below 500℃ in 2 × 10-³ s or faster (i.e., cooling rate is approximately 1,000,000℃/s).

An amorphous solids is obtained by melting an appropriate metallic alloy and cooling at a rate of 1,000,000 oC/s or higher. When cooling at a rate of 100 oC/s or lower, an ordinary metal is obtained in which there is long-range atomic order are called crystalline solids. However, an amorphous metal has no crystal, in which there is no long-range order of the positions of the atoms.

Compared with ordinary metals, amorphous metals exhibit excellent performance, such as high resistances to corrosion and abrasion, good soft magnetism (easily magnetized),and good catalytic performance (easily ionized).

High corrosion resistance	Corrosion resistance of amorphous metals is more than ten thousands times larger than that of stainless steels.
Hardness with good ductility	Compared to ordinal metals, amorphous metals have about 3 to 10 times harder with good ductility.
Easy magnetism	Being random structure, amorphous metals have easy magnetic characteristics.

Using a conventional spraying gun, melting metal remains to be crystalline solid due to insufficient cooling rate. However, by newly developed spraying gun, melting metals become amorphous after ultra rapid cooling.

Fe-Cr amorphous metals have high corrosion resistance, hardly-oxidization, abrasion resistance. This amorphous materials are iron-based, chromium-containing. They surpass stainless steels. Furthermore, 35%-Cr amorphous metals have more corrosion-resistant than Hastelloy C that is known to be the highest corrosion resistance. In Vickers hardness (HV) order, they are three to four times harder than Hastelloy C.

(Weight loss after 1000 hours of dipping)

-	Fe-35Cr	Fe-16Cr	Fe-10Cr	Ni-Mo	HastelloyC
35%HCL	◎	×	×	◎	×
98%H₂SO₄	◎	◎	◎	◎	◎
60%HNO₃	◎	◎	◎	×	◎
NaOCL	◎	◎	◎	◎	×
H₃PO₄+HF	◎	×	×	－	×
Aqua regia	◎	◎	○	×	×
Hardness（Hv）	1100	900	880	1000	330
Weight loss	◎Less than 1%　 ○1% or more but less than 5% ×5% or more

Application to impellers and shaft sleeves of slurry pumps

Both corrosion- and abrasion-resistant are needed because in the slurry pumps impellers and shaft sleeves are always corroded and eroded by chemical slurry.
Amorphous metals coating of these components have much more durable, with less corrosion and wear, compared to conventional stainless steel components.

Application to magnetostrictive torque sensor

We have successfully developed the world's first high-sensitivity, fast-response magnetostrictive torque sensor jointly with SAN-E TEC Co., Ltd. and Tohoku University. The torque sensor has been used in power-assisted bicycles and in the power steering of automobiles.

Magnetostriction is a property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetization. The variation of material's magnetization due to the applied magnetic field changes the magnetostrictive strain until reaching its saturation.

High corrosion- and abrasion-resistance

Shaft sleeves of slurry pumps, impellers of slurry pumps,Chemical tanks, sink rolls of acid pickling baths

Magnetic characteristics

Torque sensors, motor cores, iron cores of power transformers Magnetic shields

Mechanical characteristics

Conveyor rolls, separators of fuels cells, cutters

Project	Development of large amorphous or nano-structured metal film using newly thermal spraying gun.
Overview	The project aims to develop production process of high performance amorphous or nano-structured metal films with mass-production and low-cost. The amorphous films will be applied to fuel cells for electric automobiles, which will reduce global warming.
Period	August 1, 2010 to February 29, 2012

For inquiries about contents

please

FAX：+81-6-6555-4026

E-mail：Amorphouspost@nakayama-steel.co.jp

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