The main problem with ceramics used in cutting tools is related to the unpredictable failures caused by the brittle fracturing of ceramic inserts, which is critical for the intermittent milling of cyclic loading. A 125-mm-diameter eight-toothed end mill, with a mechanical fastening of ceramic inserts, was used as a cutting tool for milling hardened steel (102Cr6). For the experiments, square inserts of the Al2O3 + SiC ceramic were used and compared with the samples made of Al2O3 + TiC to confirm the obtained results. The samples were coated with diamond-like coating (DLC), TiZrN, and TiCrAlN coatings, and their bending strength and adhesion were investigated. Investigations into the friction coefficient of the samples and operational tests were also carried out. The effect of smoothing the microroughness and surface defects in comparison with uncoated inserts, which are characteristic of the abrasive processing of ceramics, was investigated and analyzed. The process developed by the authors of the coating process allows for the cleaning and activation of the surface of ceramic inserts using high-energy gas atoms. The impact of these particles on the cutting edge of the insert ensures its sharpening and reduces the radius of curvature of its cutting edges.
-Presently, the modifying multilayer composite coatings have been increasingly used for upgrading performance characteristics of different products. The quality of these coatings and, consequently, efficiency of product properties modification strongly depends on the coating properties such as hardness and adhesive strength of the "coating-substrate" interface and coating interlayer boundaries. Therefore, in present paper a problem of improving accuracy of measurement and control of desired parameters of multilayer composite wear-resistant coatings is considered. An analysis of applied control methods and their quality indicators and capabilities is carried out. An approach to control the surface characteristics of products having the coatings as well as results of research of adhesion parameters and hardness of a wide range of the latest-generation multilayer composite wear-resistant coatings are presented.
This paper presents experimental studies of the influence of surface plastic deformation (SPD) (roller burnishing) on the properties of the surface layer of a part “guide apparatus” of the centrifugal submersible pump for oil production. The parts made of composite powder alloys based on the iron-copper system were taken as an object of researches. The microstructure of the surface layer of the samples, surface roughness, microhardness, and hardness were studied. Testing of the samples for the surface layer resistance to abrasive wear according to the Calotest method showed a decrease in the wear intensity by 1.5–1.6 times in comparison to samples without SPD.
The paper presents a series of experimental results for assessing the effect of duplex vacuum-plasma processing as sequential ion nitriding and coating (Nb–Ti–Al–V) N on the characteristics of the surface layer and the wear rate of complex profile tools as herringbone broaches and gear-shaping cutters from high-speed steels powder during machining a heat-resistant nickel-based alloy. The rational duplex processing modes for each type of multi-profile cutting tool under investigation were established. Tests of the tool after duplex processing under conditions close to those encountered in production showed an increase in the operational durability of herringbone broaches and gear-shaping cutters up to two times in comparison with the original tool.
Abstract. The technological principles of low-temperature deposition of multilayer vacuum-plasma coatings with the increased operational properties on various types of die steels with the assistance of accelerated argon molecules beam are offered in the article. Four standard architecture of vacuum-plasma coatings -Ti/(Ti,Zr)N, Cr/CrN, TiN/TiCN/(Ti,Cr)N and Ti/(Ti,Al)N are considered. It is shown that deposition of vacuum-plasma coatings of the listed structures at the optimum modes considerably reduces intensity of wear of shearing dies therefore quality of shaped products several times increases.
This paper discusses the results of a study focused on the nature of the interaction of Me-MeN-(Me,Mo,Al)N coatings (where Me = zirconium (Zr), titanium (Ti), or chromium (Cr)) with a contact medium based on the Ni-Cr system. The studies were carried out during the turning of nickel–chromium alloy at different cutting speeds. The hardness of the coatings was found, and their nanostructure and phase composition were studied. The experiments were conducted using transmission electron microscopy (TEM), X-ray diffraction (XRD), and selected area electron diffraction (SAED). According to the studies, at elevated cutting speeds, the highest wear resistance is demonstrated by the tools with the ZrN-based coating, while at lower cutting speeds, the tools with the TiN- and CrN-based coatings had higher wear resistance. At elevated cutting speeds, the experiments detected the active formation of oxides in the ZrN-based coating and less active formation of oxides in the CrN-based coating. No formation of oxides was detected in the TiN-based coating. The patterns of cracking in the coatings were also studied.
The efficiency of diamond-like carbon (DLC) coatings deposited by CVD- and PVD-technologies to increase the wear resistance of tungsten carbide end mills for aluminum alloy processing was experimentally studied. A complex of metallophysics studies was carried out including SEM analysis of coating surface, microrelief, a ratio between sp3- and sp2-bonds, and the microhardness of coatings obtained by nanoindentation. The final stage of the research addresses the operational testing of end mills during processing of high-strength aluminum alloy AlZn5.5MgCu.
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