Effects Of Deposition Parameters On Microstructure And Properties Of TiAlN Cutting Tool Coatings Prepared By Magnetron Sputtering

Coated cutting tools are widely used for cutting application because of their good toughness and abrasion resistance. As a main coating of cutting tools with attractive properties such as high hardness and oxidation-resistance, TiAIN coating is the milestone in the process of development of coating materials. Preparing and investigating TiAlN coating may be meaningful for developing a new coating material with complex micro structure and desirable properties. In order to obtain certain properties to adapt the machining conditions of hard-cutting materials like Ti alloys, TiAl-X-N coatings are more widely investigated basing on the addition of further elements to TiAIN coating, which may form the so-called nanocomposite with better wear and oxidation resistance. Magnetron sputtering technology is successfully applied for preparing hard coatings as reasons of its adaption to most materials, high deposition rates, stability, strong adhesive force and so on.As the backgrounds mentioned above, the aim of present work is to deposite TiAIN and TiAlSiN coatings by magnetron sputtering technology, and the influence of deposition parameters such of bias voltage, target power and N2 partial pressure on the TiAIN coatings' micro-structure and mechanical properties was focused. Whether the addition of Si will improve the TiAlSiN coatings properties was also mainly investigated. Then the obtained coatings with good properties were deposited on uncoated cutting inserts and milling tests were performed to verify the coatings'function. AFM and FE-SEM was used to detect the evolution of surface morphology and cross-section morphology. Thickness of coatings was evaluated using SEM, EDS attached to the SEM was done to evaluate the composition of coatings. The phases of these coating was characterized by X-ray diffraction using CuKa. The mechanical properties of the films, such as Nano-hardness and Young's modulus were measured by Nano-indentation method, and adhesive force is measured by material surface performance tester.(1) The TiAIN coatings deposited by magnetron sputtering had a thickness of about 1-3 ?m, had dense and fine morpoloyg, and the prefered orientation converted from(111) to (200) under high bias voltage, target power, and N2 partial pressure.(2) The hardness would increase, reach a maxmum and decrease with an increase of bias voltage and target power, and would increase with an increase of N2 partial pressure because of fine grains and (200) preferred orientation. The TiAlN coating had a maxmum hardness of 26 GPa under deposition parameters of -80V,900W and 50%(total pressure 0.4 Pa). The adhesive force would decrease with an increase of bias voltage and N2 partial pressure, and target power was not significant in influencing adhesive force. The TiAlN coating had a maxmum adhesive force of 57N under deposited parameters of -80V,900W and 20%(total pressure 0.4 Pa).(4) TiAlN coating was deposited on cemented carbide cutting inserts and the milling tests were performed, the results showed that TiAlN coating could protect the cutting inserts from abrasion and extend cutting time to more than twice.(5) As for TiAlSiN coating deposited by magnetron sputtering, with Si content increasing, the grains became finer and the degree of (200) preferred orientation increased. When Si content was 7 at.%, TiAlSiN coating had a maxmum hardness of 34GPa, and the adhesive force did not reduce, keeping at the range of 70-80N.