The Research Of Sueface Characteristics And Corrosion Resistance Of Tantalum Thin Films Deposited On 30CrMnSiNi2A Steel By Dc Bias-Voltage Sputtering

Tantalum has been widely used in spaceflight, motor, military and chemical industry, because of high melting point, excellent corrosion resistance and good conductivity. Magneton sputtering is usually used in tantalum depositing, but the target utilization of magneton sputtering is low. So it would be costly to fabricate tantalum film using magneton sputtering. The film, deposited by DC bias-voltage sputtering, is uniform. What is more, the manipulation of DC bias-voltage sputtering is easier, and the cost is lower, comparing to magneton sputterin. So DC bias-voltage sputtering was used in this paper, to deposite tantalum film on he surface of high-strength steel. The influence of depositting parameter (working pressure, bia voltage, temperature and depositting time) on the composition and structure of tantalum film was investaged. The results showed that, the film growed in the form of three-dimensional island; with the increasing of substrate temperature, the depositing rate decreased at first, and then raised; with the increasing of working pressure and bias, the depositing rate raised at first, and then decreased; part of film was oxidated, and the composition of the film was Ta, Ta₂O, TaO, TaO2, Ta₂O₅ and TaC.In order to reduce the content of oxygen in Ta film, two methods was carried out to avoid the oxidatation of tantalum film. One method was inputting H2 when depositting; the other method was heatting the vacuum chamber to remove the adsorbed gas on chamber wall.The results showed that the content of oxygen reduced after using the two methods. What's more, the inputting of H2 had little effect on the uniformity of Ta film. The roughness of film increased with the increasing of Ar pressure. After heating the vacuum chamber, the composition of the film wasα-Ta,β-Ta and Ta₂O₅.The corrosion reaiatance and nanohardness of lower oxygen content tantalum film was analyzed. The result of nano-hardness showed that the hardness was 8GPa¹3GPa. With the increasing of working pressure and bias, the hardness increased; with the increasing of substrate temperature and depositing time, the hardness raised at first, and then decreased. The result of salt-mist test showed that, the samples with Ta film were 1⁵ level higher than original sample. The result of electrochemical tests showed that, the corrosion potential increased and the corrosion current density decreased, comparing to the original sample. That is to say, the corrosion resistance of high- strength steel enhanced, because of the protection of tantalum film.