Sulfidation (British spelling alsosulphidation) is a process of installingsulfide ions in a material or molecule. The process is widely used to convert oxides to sulfides but is also related to corrosion and surface modification.
Sulfidation is relevant to the formation ofsulfide minerals.[1]
A large scale application of sulfidation is the conversion of molybdenum oxides to the corresponding sulfides. This conversion is a step in the preparation of catalysts forhydrodesulfurization whereinalumina impregnated withmolybdate salts are converted tomolybdenum disulfide by the action ofhydrogen sulfide.
Inorganosulfur chemistry, sulfiding is often called thiation. The preparation ofthioamides fromamides involves thiation. A typical reagent isphosphorus pentasulfide (P4S10). The idealized equation for this conversion is:
This conversion where an oxygen atom in the amide function is replaced by a sulfur atom involves no redox reaction.
It is known that aluminum improves the sulfidation resistance of iron alloys.[2]The sulfidation oftungsten is a multiple step process. The first step is anoxidation reaction, converting thetungsten to atungsten bronze on the surface of the object. The tungsten bronze coating is then converted to asulfide.[3]
One commonly encountered occurrence of sulfidation in manufacturing environments involves the sulfidic corrosion of metal piping.[4] The increased resistance to corrosion found in stainless steel is attributed to a layer ofchromium oxide that forms due tooxidation of thechromium found in the alloy.[4]
The process of liquid sulfidation has also been used in the manufacturing ofdiamond-like carbon films. These films are generally used to coat surfaces to reduce the wear due to friction. The inclusion of sulfidation in the process has been shown to reduce thefriction coefficient of the diamond-like carbon film.[5]