HTW Germany


HTW Hochtemperatur-
Werkstoffe GmbH

Tel.: +49 (0)8271 81 86 10
Fax: +49 (0)8271 73 72
info@htw-germany.com

Chemical Applications

Due to its exceptional properties, glassy carbon SIGRADUR® is very advantageous for many different applications in the chemical industry. SIGRADUR® offers a high corrosion resistance which makes it suitable for the chemical analysis. Compared with conventional laboratory equipment fabricated in platinum, gold and other corrosion resistant metals, special ceramics and fluoric plastics, equipment manufactured from SIGRADUR® affords a number of major advantages:
The product range includes crucibles, beakers, boats and dishes for fuming-off, evaporating, melting and decomposition. Examples illustrating the use of SIGRADUR® G for melt decomposition are shown in table 1.

SIGRADUR® is resistant against the wet decomposition agents listed in table 2 and displays no corrosion induced wear, even after frequent use.

Glassy carbon is used in electro-chemistry due to its electrical conductivity and high corrosion resistance. Examples for the use of SIGRADUR® electrodes are the cyclic voltammetry, detectors in high pressure liquid chromatography and the organic electro synthesis.

The high strength of the gas-impermeable, isotropic material is an essential requirement for SIGRADUR® components subjected to static and dynamic stresses for laboratory and full-scale plant applications. SIGRADUR® reaction tubes and linings for pressure vessels have proved to be successful in regular service.

Table

Table 1: Use of SIGRADUR® G for melt decomposition

Decomposing agent
Decomposition of
KHSO4 - K2S2O7
Fully annealed oxides of iron, titanium, zirconium; ilmenite, magnetite, chromite, columbite, fluoric plastics
H3BO3 - B2O3
Corundum, sand, silicates, titanite, enamel, barium sulphate
KHF2
Beryllium, columbite, cassiterite, chromite, rutile, zirconium, slags
Borates1), Spectromelt® decomposition agent1)
Slags, cement, aluminium silicate, catalysts
NaOH, KOH
Monazite, bauxite, red mud, tungsten ores, rutile, glass, tin oxide
Alkali metal carbonates
Manganese ores, alkali-lime glasses, beryllium, glazes, refractory materials, slags, baryte, tungsten ores, cryolite, iron ores
Na2O2 + NaOH or Na2CO3
Titanium slag, chromium ores, ferrophosphorus, hard metal, ferro alloys, chromite, beryllium, rutile, zirconium, niobium-tantalum ores, ilmenite
KNO3 + NaOH or Na2CO3
Pyrite, zinc sulphide, arsenopyrite, ferrotungsten, silicon carbide, biological materials
1) Decomposition of products for purposes including x-ray fluorescence analysis
Table

Table 2: Use of SIGRADUR® G for wet decomposition

Decomposing agent
Compositionparts by weight
Decomposition of
HF
Silicon nitride, rare earths, columbite
HF/H2SO4
10:1
Columbite and zirconium ores
HF/HNO3
1:2
Ferro alloys, silicides, bearing metals
HF/HNO3/HCl
1:1:3
Ti-, Mo-, Sn-, Zr-, U-, Pt-alloys
HF/HNO3/H2SO4
20:1:2
Silicates, bauxite, ferro and germanium alloys
HF/HNO3/HClO4
30:1:5
Silver ores, raw phosphates, silicates
HF/HCl/HClO4
6:2:1
Slags, molybdenum sulphide, molybdenum ores
HF/HCl/H2SO4
10:2:1
Silicates, slags, zirconium compounds
HF/HCl
1:1
Silicon nitride
HF/H3PO4
4:1
Mullite, germanium ores
HF/HClO4
4:1
Organic substances, decomposition involving removal of fluoride ion
HClO3
Organic substances
HClO3/HCl
1:1
Pd-, Cd-, Al-, Mg-alloys, indium, white metal
HClO3/HCl/HNO3
5:5:1
Tin alloys, pyrite and tungsten ores
HClO4
Steels, organic substances
HCl/HNO3
3:1
Ores, phosphates, platinum metals
H3PO4
Zeolites, ferrites, kaolin, quartz
Used reagents
Concentration
HNO3
65%
H2SO4
96%
HCl
37%
HF
40%
H3PO4
80%
HClO4
60%
HClO3
28% from KClO3 and dilute HClO4


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