Tungsten sheets, plates, sputtering targets

Use

Tungsten, which is classified in the VI A group, is characterized by the maximal strength of its inter-atomic bonds; the highest melting point among high-melting metals, of 3420 ^оС; a high density of 19.3 g/cm³ ; high durability, heat conductivity, and hardness (HV30 >460), resistence to creeping and stress-rupture strength (significantly higher than those of molybdenum, tantalum, or niobium at a temperature, for example, of 1100 °С). Compared to molybdenum, pure tungsten has a higher recrystallization temperature – approximately 1350 °С, 4-5 times greater vapor pressure and evaporation rate; a lower thermal expansion coefficient (4.2·10^-6 at 20 °) and a low electric conductivity (0.05·10^-6 Оm·m).

Contemporary powder metallurgy methods ensure a high level of tungsten purity in terms of metallic and interstitial impurities (C, N, O, H), a small-grain structure necessary for use in the electronics industry and as a heat-resistant structural material in electrical technology and other devices that operate at extremely high temperatures.

Various equipment for high-temperature vacuum and hydrogen furnaces (thermal screens, radiators, mounts, suspension mounts, and other fastening parts), crucibles for smelting corundum in sapphire-growing technologies, crucibles for thermal vaporization of substances in technologies for the vacuum deposition of thin films, electrodes of plasmatrons, ignition systems of internal combusion engines and devices for measure the concentration of acidic solutions in electrochemical processes.

Sputtering targets made from highly pure tungsten are used to apply thin barrier films when metallizing semiconductor components of integral circuits.

Tungsten and its alloys are used to make heat-resistant parts for rockets that operate under extreme temperatures and intense gas erosion.

Tungsten’s low vapor pressure allows it to be used at high (up to 2300 °С) temperatures as an emitter of electrons in thermoelectric engines.

In the nuclear power industry, tungsten is used as screens for buffering the flow of radioactive radiation and ensuring the functionality of structural elements exposed to plasma under the effects of radiation and thermal-cycle loads (diverters in thermonuclear reactors).

Porous sintered tungsten is a promising material for use in the ionizers of plasma-ion rockets.

Sheets from W-PM tungsten

Chemical composition

Sheets are made from tungsten powder reduced with hydrogen from tungsten oxide. Tungsten oxide with a mass percentage of WO₃ 99.98 % (the typical value is 99.99% WO₃ without including gas-forming elements) is used as raw material

An example of the chemical composition of tungsten powder  PW1,  PW2

Brand	W, %	Element contents, ppm
		Na	Al	Si	P	K	Ca	Ti	V	Fe	Ni	Mo	∑As, Cd, Sn, Sb, Pb, Bi
PW1	>99,98	6	7	< 5	10	10	6	0,6	0,3	15	12	38	< 9,5
		∑ of admixtures, not including C, N, O, H, F,  P,  S,  Cl < 122
PW2	>99,98	0,5	1	6	6	50	10	0,1	2	10	5	55	< 3
		∑ of admixtures, not including C, N, O, H,  F,  P, S,  Cl < 160

Dimensions and surface condition

W-PM sheets and plates are made with a thickness of between 0.5 and 45 mm, with trimmed edges, or tooled in accordance with the client's needs.

The roughness of tooled surfaces is set at Ra < 10 microns.

Thickness, mm	Width, mm	Length, mm
From 0,5 to 0,7	From 20 to 250	From 50 to 1000
> 0,7 to 5,0	From 30 to 310	From 50 to 1000
> 5,0 to 7,0	From 30 to 320	From 50 to 700
> 7,0 to 15,0	From 30 to 305	From 50 to 350
> 15,0 to 20,0	From 30 to 250	From100 to 300
> 20 to 45	Up to  150*	Up to   250*

*Width and length are set depending on the plate's thickness.

Sheets and plates may be made with other maximum dimensions for width, length and thickness—for example, with a thickness starting at 0.3 mm—based on the clien't wishes.

Nonflatness

The nonflatness of thin sheets with a thickness of up to 3 mm is as follows: < 2 mm per 100 mm of length; and, for sheets with a thickness of more than 3 mm with no tooling: < 1 mm per 100 mm of length.

At the client's request, sheets are produced with more rigorous nonflatness requirements.

Lack of internal defects, microstrucure, density

At the client's request, sheets and plates are delivered with control for micro- and macro-structure, mechanical properties and density.

Sample microstructures of tungsten sheets with controlled parameters

Rolling of precision sheet W99,95-PM

Requirements for the chemical composition and dimensions of В99.95-PM rolled stock are set that meet the ASTM B760 standard, along with heightened surface quality requirements with respect to State Standard 23922 for W-PM sheet.

Dimensions, surface condition

Thickness, mm	Thickness allowance, % maximum	Width, mm	Length, mm
From 0,5 to 1,0	± 10	From 10 to 200	From 50 to 1000
> 1,0 to 15,0	± 10	From 10 to 310	From 50 to 1000
> 15,0 to 40,0	± 10	From 10 to 310	From 50 to 600

Maximum deviations for rolled stock width.

Thin sheet from 0.5 mm to 4.75 mm is made with trimmed edges (ends), with a width allowance of ± 1.6, or with tooled ends with a width allowance of ± 0.8 mm, unless otherwise requested by the client.

Maximum rolled stock length deviations do not exceed ± 1.6 mm per 304.8 mm of length, and camber is no more than 1.6 mm per 304.8 mm of length, unless otherwise requested by the client.

Deviations from flatness (undulation) depending on the thickness of rolled stock

Thickness, mm	Flatness deviation, %, maximum
From 0,5 to 4,75	4
> 4,75 to 15,9	5

Surface roughness of tooled rolled stock.

The parameter for roughness of a milled surface is no more than Rz 40; the parameter for roughness of a ground surface is no more than Ra 1.6.

Thermal treatment

Following pressure treatment, rolled stock is annealed for internal stress removal, unless the client has other needs regarding the condition of the material.

Chemical composition of W99.95-PM rolled stock

W99.95-PM is made from the same reduced tungsten powder as W-PM brand rolled stock (see above).

Guaranteed chemical composition of W99.95-PM rolled stock

Brand	W, % minimum*	Admixture content, ppm, maximum
		Fe	Al	Ni	Si	C	O	N
W99.95-PM	99,95	80	50	50	50	50	100	100

* the mass percentage of tungsten is determined by subtracting from 100% the total of controlled metallic admixtures, without including the gas-forming elements С, О,  N, S, H, F, Cl.

Sample chemical composition of W9.,95-PM sheet 3.5 mm

Brand	W, %	Admixture content, ppm *
		C	O	N	Fe	Al	Ni	Si	Ca	Na	K	Mo	P	S	As
W99.95-PM	99,986	15	40	20	13	2	15	6	6	6	20	45	<1	10	1

* the total content of metallic admixtures, determined using mass-spectrometry with inductively couple plasma (ICP-MS), does not exceed 0.0138 % (138 ppm).

Tungsten sputtering targets W99.95-PM

Tungsten sputtering targets are made in the form of tooled plates and discs with dimensions and surface conditions set according to the plans agreed upon with the client.

Guaranteed chemical composition of W99.95-PM sputtering targets

Brand	W,%, minimum*	Admixture content, ppm, maximum
		Fe	Al	Ni	Si	C	O	N
W99.95-PM	99,95	80	50	50	50	100	100	100
		∑ of metallic admixtures < 500 **

* the mass percentage of tungsten is determined by subtracting from 100% the total of controlled metallic admixtures without including the gas-forming elements C, O, N, S, H, F, Cl.
** metallic admixtures are determined using mass-spectrometry with inductively coupled plasma (ICP-MS).

Advantages:

 

• the chemical purity of products from metallic admixtures and harmful interstitial impurities, ensures better mechanical characteristics of the material and operating properties of the products when working at high temperatures or with radioactive loads
• it is possible to deliver rolled stock and products ranging from thin sheets to large-size plates tooled according to the client's plans
• homogenous microstructure
• varied product design to satisfy the client's individual needs