High-temperature Corrosion of AlCrTiSiN Film in Ar-1%SO 2 Gas
AlCrSiN film with a composition of 29.1Al-17.1Cr-2.1Si-51.7N in at. % was deposited on a steel substrate by cathodic arc ion plating at a thickness of 1.8 μm. It consisted of nanocrystalline hcp-AlN and fcc-CrN, where a small amount of Si was dissolved. Corrosion tests were carried out at 800 ◦C for 5–200 h in Ar-1%SO2 gas. The major corrosion reaction was oxidation owing to the high oxygen affinity of Al and Cr in the film. The formed oxide scale consisted primarily of (Al,Cr)2O3, within which Fe, Si, and S were dissolved. Even after corrosion for 200 h, the thickness of the scale was about 0.7–1.2 μm, indicating that the film had good corrosion resistance in the SO2-containing atmosphere.
Characteristics of (Cr1-x, Alx)N Films Prepared by Pulsed Laser Deposition
Chromium aluminum nitride ((Cr1-x, Alx)N) films have been successfully prepared by pulsed laser deposition (PLD). Experiments were carried out by changing the surface area ratio of the target (Al/(Cr+Al)) from 0 to 100%. From the results of energy-dispersive X-ray spectroscopy (EDS) and Rutherford backscattering spectroscopy (RBS), we have found that the metal content ratio of the film agreed well with the surface area ratio of the target. The hardness of the (Cr1-x, Alx)N films showed the maximum value (HV∼3000) at x=0.75. Phase transition from the B1 (NaCl) structure to the B4 (würtzite) structure occurred above x=0.75, which was in reasonable agreement with the theoretical prediction. The result of the oxidation test revealed that the CrN film was oxidized at approximately 600°C, whereas in the (Cr0.5, Al0.5)N film, the existence of oxide was not detected in the annealing temperature range of RT to 900°C.
Traceability strategy for gear-pitch-measuring instruments: development and calibration of a multiball artifact
There is a strong demand to ensure the traceability of gear-measuring instruments (GMIs). We propose a multiball artifact (MBA) for the evaluation of pitch-measuring accuracy. The aim of the MBA is to transfer the minimum uncertainty from a calibrated value at the National Metrology Institute of Japan (NMIJ) to a measured value of GMIs at a shop floor. The MBA is composed of equally spaced high-accuracy balls around an axis. The pitch-measuring accuracy of GMIs is evaluated by measuring the angular pitch deviation of the balls instead of the angular pitch deviation of a gear. We calibrated the angular pitch deviation using a coordinate measuring instrument (CMM) at the NMIJ and adapting a multiple-orientation technique. We proposed a calibration strategy of the angular pitch deviation. The calibration value of the pitch deviation for the MBA at the NMIJ was obtained with a measurement uncertainty (U95) of 0.2 µm. We evaluated the pitch-measuring accuracy of a GMI using the calibrated MBA. Each value of U95 for the cumulative and single pitch deviations for the left and right flanks was less than or equal to 0.5 µm. The small uncertainty was transferred from the NMIJ to the GMI.