Search

Abstract: A series of CrNx/WNy nanolayer coatings were synthesized using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™), employing one W target and three Cr targets. For comparison, a monolayer CrN coating was also grown on the same deposition system. Characterization was conducted using EDX, SEM, TEM, AFM, XRD, nanohardness indentation tester, and scratch tester. Performance of cutting tools with the nanolayer coatings was carried out via machining tests using the coated micro drills to continuously make through-thickness holes on printed circuit boards. The results showed that nanolayer CrNx/WNy coatings with various modulation period (λ) could be obtained on an industrial-size deposition machine by means of control in the current applied to the W target. Of the studied nanolayer CrNx/WNy coatings, the one with λ =27nm showed the highest nanohardness and best micro drilling performance. This nanolayer coating showed significant improvements in cutting performance as compared with the referred monolayer CrN coating. [Copyright &y& Elsevier]

In this study, the tribological characteristics and cutting performance of chromium carbide (Crx%C)-coated cemented carbide tool inserts and micron-drills were investigated in dry machining condition. Crx%C coatings have been deposited with different optical emission monitoring (OEM) set values, x%, of chromium target “poisoning” by unbalanced magnetron (UBM) sputtering and OEM control. The microstructures and mechanical properties of Crx%C coatings have been characterized by the experiments of SEM, nanoindentation and adhesion. The tribological properties of the coatings have been tested against different counterbodies under dry conditions using an oscillating friction and wear tester. Indexable inserts with Crx%C coatings were applied to turning AISI 1045 steel and JIS C5191 phosphor bronze material by a lathe. Micron-drills with Crx%C coatings were adopted in ultrahigh spindle speed (105 rpm) PCB through-hole drilling test. Experimental results indicate that the coating microstructures, mechanical properties and wear resistance vary according to the chromium content. Cr10%C-coated inserts showed the best wear resistance in AISI 1045 steel turning test. Cr50%C-coated tools have performed exceptionally well in both phosphor bronze turning and PCB through-hole drilling tests. The service life of Cr50%C-coated tool is 15 times greater than that of an uncoated tool in PCB through-hole drilling test. [Copyright &y& Elsevier]

The chromium doping in MoS2–Crx% coatings improves their mechanical properties, adhesion strength and tribological properties. An investigation of the coating system MoS2–Crx% with varying chromium contents deposited on tungsten carbide disks by unbalanced magnetron sputtering was carried out. The results of hardness, elastic modulus, scratch adhesion and tribological properties of these coatings were reported. The tribological properties of the coatings against copper, AISI 52100 steel and Si3N4 ceramic balls were investigated by using an oscillation sliding test machine with a point-contact wear mode under dry condition. A Cr metal atomic percentage at 8% in the MoS2–Crx% coating was found to possess the optimum wear resistance and durability when paired with a copper, steel and ceramic ball. [Copyright &y& Elsevier]

Physical vapor deposition (PVD)-coated cutting tools are used extensively in global manufacturing for reducing production costs and improving productivity in the high-speed machining operations. In this paper, the tribological characteristics and machining performance of chromium carbide (CrxC)-coated cemented carbide tool inserts and micron-drills were assessed in dry machining. CrxC coatings have been deposited with different optical emission monitoring (OEM) set values of chromium target “poisoning” by closed field unbalanced magnetron (CFUBM) sputtering and OEM control. The microstructures and mechanical properties of CrxC coatings have been characterized by SEM, nanoindentation and adhesion techniques. The tribological properties of the coatings have been tested against different counterbodies under dry conditions using an oscillating friction and wear tester. Indexable inserts with CrxC coatings were applied to turning AISI 1045 steel and JIS C5191 phosphor bronze material by a lathe. Micron-drills with CrxC coatings were adopted in the ultra high speed (105 rpm) PCB through-hole drilling test. Experimental results indicate that the coating microstructure, mechanical properties and wear resistance vary according to the chromium content. Cr0.182C-coated inserts showed the best wear resistance in 1045 steel turning test. Cr0.688C-coated tools have excellent performance in both phosphor bronze turning and PCB through-hole drilling tests. The service life of Cr0.688C-coated tool is 15 times greater than that of an uncoated tool in PCB through-hole drilling test. [Copyright &y& Elsevier]