ICMCTF 2021 Virtual Conference Session G1: Advances in Industrial PVD, CVD and PCVD Processes and Equipment

Thermal sprayed coatings containing tungsten carbide (WC) are widely used in different industrial applications due to its high hardness, high temperature and wear resistance. As sprayed coatings containing WC usually require a second stage of remelting, after application, to enhance the final properties, which can be made using different heat sources like laser, electric arc, oxi-gas flame or a furnace. Aspects of coating quality like adherence, dilution and level of defects are strongly affected by the heat source and procedure employed. Nevertheless, there is a lack of systematic studies related to these aspects. The objective of this work was to analyze different parameters using GTAW to produce the remelting of WC-Co thermal sprayed coatings obtained by High Velocity Oxi-Fuel (HVOF) process. Samples of carbon steel were coated by HVOF using a WC-Co powder obtaining a coating of 100 microns thickness with a hardness of 1250 HV. Then, the coated samples were remelted using GTAW processes. In each case, the effect of different parameters like power, travel speed and patterns were evaluated. On the refused samples microstructural characterization, microhardness profiles and electrochemical corrosion test were done. There were obtained procedures to remelt the WC-Co coatings with low dilution. The processes produced coatings with hardness values between 1600 and 1800 HV. The resistance to corrosion was similar than the as spray condition. Nevertheless, the integrity of the interphase was strongly improved in both cases.

Acknowledgments

The authors want to acknowledge to RIJEZA-Brasil for providing the coated material and to INTI-Argentina and ITA-Brasil for the wear tests.

Since HIPIMS enter the coating scene a lot of investigations on this topic had been carried out. Discovering new properties, different material behavior compared to convention sputtered coatings and better performance in cutting, forming and tribology applications. Most of the investigations were done on small scale deposition units. But bringing this technology to industry, larger units are needed and also process upscaling is needed.

Today real production of coated parts require not only good coating properties also production related topics like reliability, easy maintenance, cost per part and flexibility of the coating unit itself plays an important role.

In this regard different HIPIMS coatings from AlCrN-based, AlTiN-based and hydrogen free DLC such as ta-C systems were deposited on industrial scale units for tribology and tool applications. The applied coatings were investigated concerning mechanical film properties like hardness, Young´s Modulus, chemical properties like composition and phase formation. To verify the performance of the coating machine and the deposited coatings, industrial tests in automotive and tool applications are carried out. The obtained results shown, that the HIPIMS technology is ready for serial production in a modern production environment.

Tin oxide (SnO₂) has been widely explored for various applications due to its excellent n-type semiconductor properties, low resistance, and high optical transparency in the visible range. However, few studies on the preparation of SnO₂ films using high power pulsed magnetron sputtering have been reported. Oxygen content is a critical parameter in the practice of SnO₂ thin films by high-power pulsed magnetron sputtering. the average free range of Sn atoms is usually much smaller than O atoms. SnO₂ films deposited in a pure Ar atmosphere are likely to be oxygen-deficient and form O vacancies. and such oxygen vacancies will cause lattice distortion, which will affect the mobility of charge carriers in the SnO₂ film. Therefore, oxygen is the main factor affecting the electrical conductivity of SnO₂ films.

In this paper, the reaction mode of high-power pulsed reactive magnetron sputtering at different oxygen partial pressures and the crystal structure and infrared transparent conductive properties of SnO₂ films prepared at 600°C were investigated. The crystal structures and properties of infrared transparent SnO₂ films deposited by high-power pulsed magnetron sputtering at different oxygen partial pressures from 10 to 24 sccm were investigated. For the SnO₂ films deposited with 10~14 sccm oxygen partial pressure, the reaction mode is dominated by the metallic mode, and the polar unsaturated (101) plane is the preferred orientation of the film crystals. For SnO₂ films deposited with oxygen partial pressures of 16 to 18 sccm, the reaction mode is dominated by the transition mode, and the (110) plane shows a preferred orientation. In the deposition process with oxygen partial pressure greater than 18 sccm, the reaction proceeds in the poisoning mode. As the oxygen partial pressure increases, the carrier concentration decreases to 2.335×10¹⁵ cm^-3; the mobility increases to ~15 cm²/Vs, and the IR transmittance at 4 μm increases. At the same time, the electrical properties of the prepared SnO₂ films deteriorate due to the oversupply of O₂, with resistivity up to 5.029×10² Ω•cm².

Magnetron sputtering is a mature and well establish PVD deposition technique. Since the introduction of commercial planar magnetrons in the 1970s there are few vacuum coating sectors that haven’t been touched by successful implementations of this deposition technique. In the 1970s the semiconductor industry was revolutinonized by the introduction of planar magnetron sputtering as an alternative to evaporation and diode sputtering. Nearly forty years later, still magnetron sputtering is at the heart of many of the manufacturing processes from small to large area, with different degrees of functionality, from decorative, to energy, transport, architectural, automotive, aerospace, display, photovoltaic, thermal solar, electronics, etc.