Investigation of Chemically Vapor Deposited Tantalum for Medium Caliber Gun Barrel Protection

Abstract

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Tantalum coating prepared by APCVD and in-vivo biological evaluation

“…The organic cases can leave behind impurities [15]. The Ta halide TaCl 5 is often selected as the CVD precursor for implant coatings [2,5,6,11] because it can be reduced by H 2 to produce Ta at the lowest reaction temperature of the halides [17]. The reaction of TaCl 5 with H 2 forms HCl, which corrodes the equipment and the substrates.…”

“…The reaction of TaCl 5 with H 2 forms HCl, which corrodes the equipment and the substrates. The melting and boiling points of TaCl 5 are 216 and 242°C, respectively [17]. Thus, it is difficult to obtain a stable TaCl 5 partial pressure which is important to CVD process.…”

“…97 and 230°C. At a given temperature, TaF 5 has a higher vapour pressure than TaCl 5 [17]. Furthermore, the HF produced in the TaF 5 –H 2 system is less corrosive towards the equipment than HCl.…”

“…Part II had a preferred orientation in α-Ta (110) direction, with small peaks also observed at 2θ = 68 and 73°corresponding to ß-Ta. Such a mixture of phases has been encountered in low-pressure CVD[16,17] depending on deposition conditions.The coating orientation resulting from CVD depends strongly on operating conditions, such as adsorption[21] and concentration of reaction and byproducts[22]. Along the flow direction, increasing concentration of HF caused surface active sites on the crystal planes to be more adsorbed by HF than by H 2 (This is because the heat of adsorption of HF = 3680 J/mol [Equation(3)] is more than the heat of adsorption of H 2 = 840J/mol[20]).…”

Inhibitor performance and the preparation study of urea formaldehyde resin matrix composite particle

“…To inhibit gun tube wear and erosion, domestic and foreign scholars have proposed many possible methods including the coatings of inner bore of barrel, optimization of shape and cartridge belt material of artillery, manufacturing technology of composite pipe, cooling technology of barrel, barrel self-repair technology, low temperature propellant and inhibitor additives technology [1][2][3][4][5][6][7][8]. Among them, the inhibitor additives technology, a kind of simple and effective method, has caught more and more attention.…”