| Summary: | Nanoscale TiAlCN/VCN multilayer coating was deposited in an industrial size 1000x4 Hauzer Techno Coating machine capable to operate with both unbalanced magnetron sputtering (UBMS) and high power impulse magnetron sputtering (HIPIMS) mode. The work was directed to study the impact of HIPIMS on the microstructure of the nanoscale TiAlCN/VCN coating, in relation to its properties at both room and elevated temperatures. TiAlCN/VCN coatings were deposited by three different ways in combination of reactive UBM and HIPIMS technique. These are (i) reactive pure UBMS, (ii) reactive combined UBMS and HIPIMS, (iii) reactive pure HIPIMS. The microstructure and mechanical properties of the nanoscale TiAlCN/VCN coatings deposited in all the above combination of deposition have been studied. In all three cases, coatings were deposited in three major steps: (a) HIPIMS etching by Ar[+] + V[+] ions (b) a 300 nm thick TiAIN base layer deposition in Ar + N[2] atmosphere followed by 2.5 pm thick TiAlCN/VCN coating deposition in mixed Ar+N[2]+CH[4] reactive atmosphere. PVD chamber furnished with two pairs of opposing magnetrons with TiAl and V targets were utilised deposit this coating. During the second case of combined deposition, two opposing magnetrons were enabled to operate in HIPIMS mode and other two magnetrons were operated in UBMS mode, where as in third case only two opposing targets with HIPIMS power supply were utilised to deposit the TiAlCN/VCN coating respectively. In all the three cases, deposition parameters such as bias voltage (U[b] = -75V), deposition temperature (T[s]= 450 °C) and total pressure of reactive gas mixture (Ar+N[2]+CH[4]; P = 4 X 10[-3] mbar) were maintained at similar conditions. The V+ HIPIMS etching used in all three processes has shown excellent adhesion (Lc > 50) of the coating to the substrate. The plasma compositional analysis of V+ HIPIMS etching has shown high metal-to-gas ion ratio with ionization states of V up to 5+. The ionic composition of the HIPIMS plasma as a function of discharge current was analysed by plasma sampling using energy-resolved mass spectrometery. During the coating of TiAlCN/VCN, the plasma analysis has confirmed the higher production rate of metal ions and free carbon in case of HIPIMS-UBM in contrast to pure UBM. This has resulted to a denser closed columnar microstructure of the coating during the HDPIMS-UBM technique than UBM. The formation of graded like microstructure achieved during reactive pure HIPIMS case, further plants the importance of HIPIMS in producing advanced nanostructured coatings for high technology applications.
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