OBRABOTKAMETALLOV MATERIAL SCIENCE Том 23 № 3 2021 EQUIPMEN . INSTRUM TS Vol. 7 No. 2 2025 of obtaining semi-finished blanks in the form of cylindrical rods with a length of 120 mm included the following technological operations: cold isostatic pressing of powder in a silicone mould at a pressure of 200–300 MPa; preliminary sintering (bisquit firing) in an air environment; rough turning with an outer diameter tolerance of h9; final sintering in a vacuum high-temperature furnace; circular grinding to the final size with a diameter tolerance of h6; diamond cutting of the rod into blanks with a thickness allowance; flat grinding to the final size in thickness. Structurally, the cutting insert had a round shape and alphanumeric designation RNGN 120400-01 according to GOST 25003-81 “Ceramic indexable throw-away inserts for cutting tools. Specifications”, which corresponds to a thickness of 4.76 mm and a diameter of 12.70 mm without additional chamfers and ledges on the rake surface. A total of 5 (five) cutting inserts were produced, the faces of each insert was pre-grinded on a surface grinding machine mod. 3D711AF11 using diamond wheel 1A1 250×20×5×5×76 AC4 125/100 100% B2-01, special multi-place tooling and abundant supply of water-based coolant. Visual inspection for the presence of surface cracks was performed using a magnifying glass with magnification 20×, and random inspection was carried out in the process of evaluating the initial condition of the cutting inserts on a scanning electron microscope at magnifications 500× and more (Fig. 1). a b Fig. 1. Ceramic inserts (a) and electron microscopy of the cutting edge (b) in the initial state Fig. 2. Mandrel with a ceramic insert attached The ceramic cutting inserts were mounted in the CRDNN 2525M 12-ID holder by Sandvik Coromant (Switzerland) using a carbide pad by pressing from above (Fig. 2). The initial ceramic powders and sintered products were studied using certified equipment. Elemental composition was determined on X-ray fluorescence wave dispersive spectrometer XRF-1800 mod. XRF-1800 by Shimadzu (Japan). The appearance of powders and their particle size distribution were studied on a scanning electronmicroscopemod. Mira 3LMU by Tescan (Czech Republic). X X-ray structural analysis was carried out on X-ray diffractometer mod. DRON 8N from JSC “IC “Burevestnik” (St. Petersburg), equipped with a microstrip X-ray detector mod. Mythen 2R 1D by Dectris (Japan). X-ray images were taken with CuKα-radiation (λ = 0.15406 nm) in the range of angles 2θ 20–90°. The detector scanning step was 0.1° and the data acquisition time was 30 s. The specific surface area of the initial powders was determined on the device mod. SORBI-M of LLC “META” (Novosibirsk), by nitrogen adsorption by the 4-point Brunauer-Emmett-Taylor method (theory of polymolecular adsorption).
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