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The Basics, Starting Out
Barrel burnout
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<blockquote data-quote="Hugnot" data-source="post: 2546474" data-attributes="member: 115658"><p>My thinking is that both Tungsten Disulfide & Molybdenum Disulfide are sufides and being such are subject to decomposition where air (oxygen), water (moisture) and warmth (heat) are present. A product of sulfide decomposition would be sulfuric acid, corrosive stuff. The wikipedia explanation in regard to WS2 decomposition is sort to academic but gives some idea of the decomposition process. Granted, rifle barrel bores are sort of dark inside (no light of suitable wavelength) but the other elements like water (moisture) & heat are present. "Monolayer" means 1 molecule thick and it is likely that any WS2 coating would greatly exceed that. Long term exposures of WS2 to moisture & heat were not addressed. Looks like sunshine, humidity & warmth might make for WS2 liabilities on exposed chrome-moly steel surfaces.</p><p></p><p> I can't see any advantages of appling internal lubrication to rifle bores because any lubricant would be quickly worn off by hot powder burning gas & bullet friction. Chrome oxide would be formed on stainless steel barrel surfaces and that would act as a protective coating retarding rust, shown by rusty patches. Tiny micro size pitting might occur, not visible by bore scope magnification.</p><p></p><p>[URL unfurl="true"]https://en.wikipedia.org/wiki/Tungsten_disulfide[/URL]</p><p></p><p>"Although it has long been thought that WS<sub>2</sub> is relatively stable in ambient air, recent reports on the ambient air oxidation of monolayer WS<sub>2</sub> have found this to not be the case. In the monolayer form, WS<sub>2</sub> is converted rather rapidly (over the course of days in ambient light and atmosphere) to tungsten oxide via a photo-oxidation reaction involving visible wavelengths of light readily absorbed by monolayer WS<sub>2</sub> (< ~660 nm; > ~1.88 eV).<sup><a href="https://en.wikipedia.org/wiki/Tungsten_disulfide#cite_note-Photoxidation_ws2-8" target="_blank">[8]</a></sup> In addition to light of suitable wavelength, the reaction likely requires both <a href="https://en.wikipedia.org/wiki/Oxygen" target="_blank">oxygen</a> and <a href="https://en.wikipedia.org/wiki/Water" target="_blank">water</a> to proceed, with the water thought to act as a <a href="https://en.wikipedia.org/wiki/Catalyst" target="_blank">catalyst</a> for oxidation. The products of the reaction likely include various tungsten oxide species and <a href="https://en.wikipedia.org/wiki/Sulfuric_acid" target="_blank">sulfuric acid</a>. The oxidation of other semiconductor transition metal dichalcogenides (S-TMDs) such as MoS<sub>2</sub>, has similarly been observed to occur in ambient light and atmospheric conditions.<sup><a href="https://en.wikipedia.org/wiki/Tungsten_disulfide#cite_note-Mos2_ambient-9" target="_blank">[9]</a>"</sup></p></blockquote><p></p>
[QUOTE="Hugnot, post: 2546474, member: 115658"] My thinking is that both Tungsten Disulfide & Molybdenum Disulfide are sufides and being such are subject to decomposition where air (oxygen), water (moisture) and warmth (heat) are present. A product of sulfide decomposition would be sulfuric acid, corrosive stuff. The wikipedia explanation in regard to WS2 decomposition is sort to academic but gives some idea of the decomposition process. Granted, rifle barrel bores are sort of dark inside (no light of suitable wavelength) but the other elements like water (moisture) & heat are present. "Monolayer" means 1 molecule thick and it is likely that any WS2 coating would greatly exceed that. Long term exposures of WS2 to moisture & heat were not addressed. Looks like sunshine, humidity & warmth might make for WS2 liabilities on exposed chrome-moly steel surfaces. I can't see any advantages of appling internal lubrication to rifle bores because any lubricant would be quickly worn off by hot powder burning gas & bullet friction. Chrome oxide would be formed on stainless steel barrel surfaces and that would act as a protective coating retarding rust, shown by rusty patches. Tiny micro size pitting might occur, not visible by bore scope magnification. [URL unfurl="true"]https://en.wikipedia.org/wiki/Tungsten_disulfide[/URL] "Although it has long been thought that WS[SUB]2[/SUB] is relatively stable in ambient air, recent reports on the ambient air oxidation of monolayer WS[SUB]2[/SUB] have found this to not be the case. In the monolayer form, WS[SUB]2[/SUB] is converted rather rapidly (over the course of days in ambient light and atmosphere) to tungsten oxide via a photo-oxidation reaction involving visible wavelengths of light readily absorbed by monolayer WS[SUB]2[/SUB] (< ~660 nm; > ~1.88 eV).[SUP][URL='https://en.wikipedia.org/wiki/Tungsten_disulfide#cite_note-Photoxidation_ws2-8'][8][/URL][/SUP] In addition to light of suitable wavelength, the reaction likely requires both [URL='https://en.wikipedia.org/wiki/Oxygen']oxygen[/URL] and [URL='https://en.wikipedia.org/wiki/Water']water[/URL] to proceed, with the water thought to act as a [URL='https://en.wikipedia.org/wiki/Catalyst']catalyst[/URL] for oxidation. The products of the reaction likely include various tungsten oxide species and [URL='https://en.wikipedia.org/wiki/Sulfuric_acid']sulfuric acid[/URL]. The oxidation of other semiconductor transition metal dichalcogenides (S-TMDs) such as MoS[SUB]2[/SUB], has similarly been observed to occur in ambient light and atmospheric conditions.[SUP][URL='https://en.wikipedia.org/wiki/Tungsten_disulfide#cite_note-Mos2_ambient-9'][9][/URL]"[/SUP] [/QUOTE]
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