Ti0.5Al0.5N/CrN nano-multilayers, which are known to exhibit excellent wear resistances, were prepared using the unbalanced magnetron sputter for various periods of 2–7 nm. Ti0.5Al0.5N and CrN comprised a cubic structure in a single layer with different lattice parameters; however, Ti0.5Al0.5N/CrN exhibited a cubic structure with the same lattice parameters that formed the superlattice in the nano-multilayers. The Ti0.5Al0.5/CrN multilayer with a period of 5.0 nm exceeded the hardness of the Ti0.5Al0.5N/CrN single layer, attaining a value of 36 GPa. According to the low-angle X-ray diffraction, the Ti0.5Al0.5N/CrN multilayer maintained its as-coated structure up to 700oC and exhibited a hardness of 32 GPa. The thickness of the oxidation layer of the Ti0.5Al0.5N/CrN multilayered coating was less than 25% of that of the single layers. Thus, the Ti0.5Al0.5N/CrN multilayered coating was superior in terms of hardness and oxidation resistance as compared to its constituent single layers.

TiN and CrN thin films are among the most used coatings in machine and tool steels. TiN and CrN are deposited by arc ion plating(AIP) method. The AIP method inhibits the reaction by depositing a hard, protective coating on the material surface. In this study, the characteristics of multi-layer(TiN/CrN/TiN(TCT), CrN/TiN/CrN(CTC)) are investigated. For comparison, TiN with the same thickness as the multilayer is formed as a single layer and analyzed. Thin films formed as multilayers are well stacked. The characteristics of micro hardness and corrosion resistance are better than those of single layer TiN. The TiN/CrN peak is confirmed because both TCT and CTC are formed of the same component(TiN, CrN), and the phase is first grown in the (111) direction, which is the growth direction. However, the adhesion and abrasion resistance of the multilayer films are somewhat lower.

Chromium nitride (CrN) samples with two different layer structures (multilayer and single layer) were coated on bipolar plates of polymer electrolyte membrane fuel cells (PEMFC) using the reactive sputtering method. The effects with respect to layer structure on corrosion resistance and overall cell performance were investigated. A continuous and thin chromium nitride layer (Cr0.48 N0.52) was formed on the surface of the SUS 316L when the nitrogen flow rate was 10 sccm. The electrochemical stability of the coated layers was examined using the potentiodynamic and potentiostatic methods in the simulated corrosive circumstances of the PEMFC under 80˚C. Interfacial contact resistance (ICR) between the CrN coated sample and the gas diffusion layer was measured by using Wang's method. A single cell performance test was also conducted. The test results showed that CrN coated SUS316L with multilayer structure had excellent corrosion resistance compared to single layer structures and single cell performance results with 25 cm2 in effective area also showed the same tendency. The difference of the electrochemical properties between the single and multilayer samples was attributed to the Cr interlayer layer, which improved the corrosion resistance. Because the coating layer was damaged by pinholes, the Cr layer prevented the penetration of corrosive media into the substrate. Therefore, the CrN with a multilayer structure is an effective coating method to increase the corrosion resistance and to decrease the ICR for metallic bipolar plates in PEMFC.

아크이온 플레이팅 장치를 이용하여 STD61강 기판 위에 이온질화 전처리를 행하거나 하지 않은 후, CrN 박막을 증착하고, 대기중 700~900˚C의 온도에서 40시간동안 이들에 대한 산화거동을 연구하였다. 산화거동은 열중량분석기, X선회절기, EDS, SEM을 이용하여 조사하였다. 증착된 CrN박막은 CrN과 Cr2N의 두 상으로 구성되어 있었다. CrN박막은 보호적 Cr2O3층을 형성하여 기판을 산화로부터 보호하였다. 이온질화처리는 CrN박막의 내산화성에 영향을 주지 않았다.