Gorwth And Thermal Stability Reserach Of Cubic AlN In AlN/TiN Nano-Multilayers

The continuous improvement of social productivity is inseparable from the vigorous development of the manufacturing industry.Hard protective coatings are deposited on cutting tools to improve their cutting performance,extend their service life,and useful in reducing the cost of production,improve work efficiency.Through the formation of periodic coherent cAl N/c-Ti N superlattice structure,the Al N/Ti N nano-multilayers can obtain excellent performance of mechanical properties,oxidation resistance and wear resistance,which is very suitable for the hard protection coating for cutting tools.However,c-Al N is a metastable phase.When the thickness is too large or the external temperature is too high,c-Al N will change into w-Al N with higher stability,which will lead to the destruction of superlattice structure and the abrupt decline of coating performance.It is significant to prepare c-Al N/c-TMN superlattice coatings with high thermal stability for the high-temperature working environment of dry cutting operations.This article focused on Al N/Ti N nano-multilayers deposited by magnetron sputtering method.Influence of deposition temperature,Ti N interlayer thickness and the substrate materials on the prepartion of c-Al N/c-Ti N superlattice were explored.Also,the thermal stability of as-deposited superlattice structure were characterized and analysis of structure evolution in c-Al N/c-Ti N superlattice under hot conditions were conducted by microstructureanalysing methods such as XRD and cross-sectional TEM.The main conclusions are as follows:(1)A sufficiently high deposition temperature is conducive to the formation of c-Al N/cTi N superlattice by magnetron sputtering method.When the deposition temperature is 600 ?,c-Al N/c-Ti N superlattice structure with a small thickness(1 nm)of c-Al N layer can be prepared.(2)Compare c-Al N/c-Ti N superlattice coatings with different Ti N thicknesses.With the increase of Ti N thickness,the XRD patterns of c-Al N/c-Ti N superlattice have more satellite peaks with higher strength indicating better superlattice structure.The thickness of c-Al N can be up to about 5 nm.(3)The c-Al N/c-Ti N superlattice with a small thickness(1 nm)c-Al N layer has good thermal stability of c-Al N.After annealing at 1000 ? for 540 min,the c-Al N still maintains its cubic structure despite local damage to the layered structure.(4)After annealing at 1000 ? for 40 min and 540 min,the as-deposited c-Al N/c-Ti N superlattice with a thickness of 7 nm and 10 nm shows only a decrease in strength,but no disappearance of the XRD satellite peaks,showing even better thermal stability than the cAl N/c-Ti N with a thickness of 1 nm prepared in this paper.