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In this work, machining of the superduplex stainless steel was investigated using cemented carbide turning inserts with chemical vapor deposited (CVD) TiCN + AlO as well as physical vapor deposited (PVD) TiCN and AlTiN coatings. These three coating system were tested during finish turning operation of superduplex stainless steel. It has been found that unfavorable friction and wear conditions were observed when TiCN- and TiCN + AlO-coated tools were used. On the other hand, the AlTiN-coated tool showed a self-adaptive behavior through the formation of tribo-film of aluminum oxide that improves frictional conditions and, consequently, wear resistance during machining of SDSS. This behavior shows that the tool life for inserts coated with PVD AlTiN was approximately two times higher than CVD TiCN + AlO. Another important result that can be observed in this work is related with the surface integrity that was improved when machined with cutting inserts coated with PVD AlTiN. [ABSTRACT FROM AUTHOR]

The tribological behavior of tenfold micro/nanocrystalline CVD diamond multilayers is here investigated in self–mated configuration using ball-on-plate reciprocating wear testing. The effects of relative humidity (RH) and temperature (T) on friction and wear coefficients are assessed. The strongest effect of humidity was found on the value of the critical load (no delamination) that triples from 40 N at 10%RH to 120 N at 90%RH. Evaluation of the wear coefficients of the plates was only possible with the use of 3D optical profilometry. A valley-shaped evolution is observed for the wear coefficient of the plates, within the 10% to 90% RH range, with a minimum of about 1.7x10 -7 mm 3 N -1 .m -1 , indicative of a mild wear regime, whereas the balls have lower values in the very mild wear regime of k ~ 10 -8 mm 3 N -1 .m -1 . The clearest difference between the RH and temperature experiments is observed for the critical loads, limited to the range 40-55 N at 50-100°C, while at room temperature a value of 120 N was reached. However, the critical loads at high temperature are similar to those attained under dry conditions (≤ 25% RH) highlighting the absence of water as the load bearing medium. [ABSTRACT FROM AUTHOR]

Machining of carbon fibre reinforced polymer (CFRP) is abrasive and causes significant tool wear. The effect of tool wear on static flexural strength is investigated, using edge trimming with uncoated carbide and chemical vapour deposition (CVD) diamond coated burr style tools. Edge rounding (ER) criteria along with flank wear are used to observe tool degradation with ER shown to preferentially wear allowing the tool to become cyclically sharper and duller, corresponding to fluctuating dynamometer readings, a novelty for CFRP machining. Areal surface metrics degraded for an uncoated tool due to changes in cutting mechanism, whilst for up to 16.2 m of linear traverse, the coated tool showed limited changes. Tool wear, caused by edge trimming 7.2 m of CFRP, using an uncoated carbide tool, provided a flexural strength reduction of up to 10.5 %, directly linking tool wear to reduced mechanical strength. • Uncoated and coated tools showed cyclical sharpening of cutting edges which was reflected in cutting force measurements. • Edge radius of cutting tools obtained through focus variation are shown to be a useful metric to measure wear. • Worn, uncoated carbide tools lead to increased S a and reduced flexural strength compared to unworn. [ABSTRACT FROM AUTHOR]

The present work attempts to study the effect of important machining variables on performance characteristics such as material removal rate and tool wear in turning of Inconel 718 using chemical vapour deposition (CVD) coated tungsten carbide (WC) tool. A three dimensional machining model using Lagrangian approach has been developed using DEFORM 3D. The machining simulation is carried out to predict the flank wear and material removal rate (MRR). Flank wear is calculated using Usui’s wear model in the simulation model. The results from simulation model are compared with experimental data generated by the use of Taguchi’s L 16 orthogonal array for reducing the experimental runs. Analysis of variance (ANOVA) is performed to identify the most influencing variables for both the performance characteristics. It is found that simulation results are in good agreement with experimental results. A valid simulation models helps the tool engineers to gather relevant process related information without resorting to costly and time consuming experimentation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Superhydrophobicity occurred with PTFE-AC-coated Al after intensified anodisation. [•] This coating exhibited own roughness features in the sub-/ low-micrometre ranges. [•] Polysiloxane coatings afforded smooth surfaces with incomplete water-repellence. [•] Artificial weathering resulted in a general worsening of the wetting behaviour. [•] Both coating types displayed strong differences in their sensitivity towards wear. [•] Cross-linkages between polymer chains are prerequisite for mechanically stable SH. [Copyright &y& Elsevier]

Abstract: In the present study, adopting the optimized deposition parameters determined by orthogonal simulations, high-quality boron-doped and undoped composite diamond (BD–UCD) films with uniform thickness are deposited on both the inner hole and conical surfaces of the SiC nozzles used in the spray drying equipment. The erosion behavior of the novel diamond film is firstly evaluated in an air–sand erosion rig, with single-layer boron-doped diamond (BDD) and undoped diamond films as comparisons. Thereafter, the erosive wear performance of the BD–UCD coated nozzles is further studied under the industrial condition. The results show that the BD–UCD film exhibits an apparent increase in the erosion resistance over the other two types of diamond films. The mechanism responsible is found to be that the surface undoped diamond layer in the BD–UCD film has outstanding hardness, and boron doping can improve the adhesion between the underlying BDD layer and the substrate. Moreover, under the industrial condition, the ethylene catalytic cracking catalyzers produced with the BD–UCD coated nozzles have much more stable quality than those produced with the uncoated nozzles owing to the aperture stability of the inner hole, further proving the high erosion resistance of the BD–UCD protecting coatings. [Copyright &y& Elsevier]

Abstract: Titanium based alloys are used extensively for improving wear properties of different parts due to their high hardness contents. Titanium nitride (TiN) is among these coatings which can be deposited on surface using various techniques such as CVD, PVD and PACVD. Their weak interface with substrate is one major drawback which can increase the total wear in spite of favorite wear behavior of TiN. Disc shaped samples from AISI H13 (DIN 1.2344) steel were prepared in this study. Single TiN coating was deposited on some of them while others have experienced a TiN deposition by active screen plasma nitriding (ASPN). Hardness at the surface and depth of samples was measured through Vickers micro hardness test which revealed 1810Hv hardness as the maximum values for a dual-layered ASPN–TiN. Pin-on-disc wear test was done in order to study the wear mechanism. In this regard, the wear behavior of samples was investigated against pins from 100Cr6 (Din 1.3505) bearing steel and tungsten carbide–cobalt (WC–Co) steel. It was evidenced that the dual-layer ASPN–TiN coating has shown the least weight loss with the best wearing behavior because of its high hardness values, stable interface and acceptable resistance against peeling during wearing period. [Copyright &y& Elsevier]

Abstract: In this work, tribological wear tracks formed on moderate temperature chemical vapor deposited (MTCVD) TiB1.66N0.34 coatings were characterized by Raman spectroscopy and compared to those obtained on TiN. Therefore, ball-on-disk sliding tests against Al2O3 as well as 100Cr6 bearing steel were performed at room and elevated temperatures (25–700°C). Raman microspectroscopy was found to be essential to identify different oxide and borate phases on the wear tracks, which originate from tribochemical reactions and tribooxidation. Furthermore, it was shown that the temperature dependence of tribological reactions at the interface can successfully be studied by combining exceptional short sliding distances with post-annealing experiments at different temperatures and durations. A good correlation between the detected compounds on the wear tracks and the observed friction coefficient was achieved. In addition to the ball-on-disk tests, turning tests with Ti–B–N coated inserts were performed at various turning speeds. The detection of several oxide phases by means of Raman spectroscopy on the rake face allowed an estimation of contact temperatures and wear behavior. It was found, that the temperature of the inserts is highly affected by the cutting speed. At moderate cutting speeds of v c ≤180m/min the temperature was estimated to be ≤500°C. On the other hand, the temperature was assumed to reach values of T ≥785°C at increased cutting speeds of v c =200m/min, due to the detection of TiBO3 by Raman spectroscopy. [Copyright &y& Elsevier]

Abstract: Coated cemented carbide is a key material for cutting tools and its manufacturing includes pretreatment of the substrate surface before coating deposition. To obtain a durable tool edge, this pretreatment must achieve two objectives: high adhesive strength of the substrate-coating interface and low coating surface roughness to reduce friction with the workpiece and the chips removed during the machining process. Several methods have been researched for substrate surface pretreatment, including micro-sandblasting—the standard industrial procedure, which is an economic and effective process. In this work, a laser substrate surface treatment was examined as an alternative to micro-sandblasting, because the laser process does not produce waste material flux, allows for the selective treatment of surface areas, and involves a potentially shorter processing time per piece. A pulsed CuHBr laser (510nm, 30ns, 13.8kHz) was used, and for the tested MT-CVD TiCN/Al2O3/TiN coated cemented carbide cutting tools, the optimal laser intensity and number of laser shots were identified by trial-and-error based on the Rockwell C adhesion test. Using the optimal set of laser parameters, a group of tools was then prepared for face end milling tests on P20 mold steel. Lastly, a comparison was made of the tool lifetime, tool wear profile, and tool wear mechanisms of the experimental laser-treated tools and the commercial micro-sandblasted ones. [Copyright &y& Elsevier]