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Physical vapor deposition (PVD) coatings could affect the friction performance at the contact interface between Ti2AlNb alloy parts and tool couples. Suitable coating types could improve the friction properties of Ti2AlNb alloy while in contact with WC/Co carbide. In this study, the linear reciprocating pin–disc friction tests between the Ti2AlNb alloy and the WC/Co carbide tool couple, with the sole variation of the PVD CrAlN/(CrAlB)N/CrAlN coating were conducted within the temperature range of 25–600 °C. The antifriction properties of the Ti2AlNb alloy were estimated using the time-varied friction coefficients, the alloy wear rate, worn surface topography, worn surface element, and wear mechanism analysis. The results showed that the PVD CrAlN/(CrAlB)N/CrAlN coating could decrease the average friction coefficient and alloy wear rate compared to the uncoated WC/Co carbide couple. The apparent adhesive wear and abrasive wear of the Ti2AlNb alloy could be improved due to the PVD coating at evaluated temperatures. The PVD CrAlN/(CrAlB)N/CrAlN coating could be utilized to improve the antifriction properties of the Ti2AlNb alloy, which may be deposited on the cutting tool to improve the machining performance of Ti2AlNb alloys in future aerospace machining industry. [ABSTRACT FROM AUTHOR]

Physical vapor deposition (PVD) coatings could affect the friction performance at the contact interface between Ti2AlNb alloy parts and tool couples. Suitable coating types could improve the friction properties of Ti2AlNb alloy while in contact with WC/Co carbide. In this study, the linear reciprocating pin–disc friction tests between the Ti2AlNb alloy and the WC/Co carbide tool couple, with the sole variation of the PVD CrAlN/(CrAlB)N/CrAlN coating were conducted within the temperature range of 25–600 °C. The antifriction properties of the Ti2AlNb alloy were estimated using the time-varied friction coefficients, the alloy wear rate, worn surface topography, worn surface element, and wear mechanism analysis. The results showed that the PVD CrAlN/(CrAlB)N/CrAlN coating could decrease the average friction coefficient and alloy wear rate compared to the uncoated WC/Co carbide couple. The apparent adhesive wear and abrasive wear of the Ti2AlNb alloy could be improved due to the PVD coating at evaluated temperatures. The PVD CrAlN/(CrAlB)N/CrAlN coating could be utilized to improve the antifriction properties of the Ti2AlNb alloy, which may be deposited on the cutting tool to improve the machining performance of Ti2AlNb alloys in future aerospace machining industry.

In this paper, microstructure and some properties of various coatings based on WC-Co obtained by the High Velocity Air Fuel technique are discussed. Initially, two WC-Co 83-17 powders of standard and superfine size were examined as a feedstock for a coatings deposition on a steel substrate. A standard Amperit 526.074 powder and an Inframat superfine powder were applied. Then three different sub-micrometric powders, WC, Cr3C2 and TiC were applied to modify the microstructure of WC-Co (Amperit 526.074). The aim of the investigations was to compare the microstructure and basic properties of coatings deposited from different components. The influence of sub-micrometric additions on mechanical properties of basic coatings was analyzed. Microstructure characterization of powders by using SEM and characterization of their technological properties as well, are presented. For all manufactured coatings obtained by a High Velocity Air Fuel method, the microhardness, porosity, adhesion to a substrate, and fracture toughness were determined. An improvement in WC-Co coating properties, as a result of sub-micrometric carbides addition, was revealed.

Nowadays, there is a trend in the industry to reduce or even eliminate the use of cutting fluid in machining operations. The high costs of purchasing, using, and disposing of fluids and problems related to environmental pollution and operator health favor the dry-cutting technique. However, in some machining processes, lubrication is required. In this cases, solid lubrication may be a solution. The present study investigated the development of self-lubricating cutting tool materials by adding graphite in WC – 10 wt% Co cemented carbide and how this graphite affects the sample's mechanical properties and wear behavior. The WC - 10 wt% Co cemented carbide was prepared by spark plasma sintering (SPS), and solid graphite lubricant was added at different concentrations. The samples were mixed in a high-energy ball mill and sintered at 1200 °C under 40 MPa. Microstructure, hardness, fracture toughness, and wear analyses were performed on the samples to understand the effect of graphite addition on sintered material properties. The chemical composition of the samples was analyzed by XRD and Raman spectroscopy. The wear measurement was performed by analyzing the volume of material lost by the samples during the pin-on-disk tests. Profilometry analyzes of the samples before and after the tests made it possible to measure the volume of lost material, allowing to verify the influence of the addition of solid lubricant on the wear rate of the samples. The results of the mechanical tests show that the highest hardness and the modulus of elasticity were 1578 HV and 870 GPa, respectively. The wear presented by the samples with 1% of graphite was up to 9 times less than the standard samples. The wear mechanisms are micro-cracking and fragmentation of WC grains; however, the presence of a solid lubricant avoids the steel counterpart material transfer for the pin surface. Also, it was observed the formation of a graphite and oxide tribolayer on the worn disc surface during the tests, thus avoiding excessive wear. • The addition of graphite in the samples decreased the coefficient of friction, measured in the pin-on-disc tests. • The addition of 1% graphite presented the best result for this study. • The wear mechanism of the pin without graphite deals with microcracking and fragmentation of WC grains. • The wear mechanism in the pin involves a massive exfoliation of WC grains; this is related to decreased hardness. [ABSTRACT FROM AUTHOR]