OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 6 1 4 Research Methodology Specimens of imported hones and created analogues were used as objects of research. The mechanical properties, morphology and chemical composition of the diamond and abrasive layer of the gear hone and the annular gear functional surface were investigated. The morphology and chemical composition were studied using a Versa 3DFEI scanning double-beam electron microscope. To study the morphology of the specimens, an Altami CM0870-T optical microscope with a high-resolution camera was also used. Rubber mixtures were made on model L16M rollers. The diameter of the rollers was 100 mm. The rotation speed and the gaps between the rolls were adjustable. The developed compositions of domestic analogues of hones on diamond, abrasive and non-abrasive bases were molded with subsequent vulcanization on a PHG60-212/4 hot press. The specimens were made in the form of discs with a diameter of 50 mm and a height of 6–8 mm and plates of various sizes of the same height. Eight-piece specimens for rupture tests were made from the plates using stamps on the cutting plant. The tests were performed on a RMI-60 laboratory setup. The disc specimens were designed to determine Shore hardness on the LAC-J device. Grinding powders of green silicon carbide 64C and diamond synthetic powders of the AFM grade with a grain size of 28/20 were used as an abrasive material. Results and Discussion The imported specimen of elastic diamond hone consists of a diamond bearing layer (the functional part) and a diamond-free annular gear (hereinafter referred to as the annular gear). The annular gear is attached to a duralumin hub. A fragment of the hone teeth functional surface after straightening with a diamond tool and gear wheel honing is shown in fi gure 1. The hardness of the diamond bearing layer on the side surfaces of the hone teeth is 95–98 Shore units. The hardness of the annular gear material is 85–90 Shore units. The morphology and chemical composition were studied on a tooth fragment of the functional part of the hone, from which cross sections with a thickness of 5 mm were cut. A diamond-bearing layer is allocated along the outer contour of the tooth (fi gure 2, a); the geared rim material lies under it. In the vast majority of the studied sections, the materials have a well-defi ned interface. This is evidenced by the interface condition obtained with a 50× magnifi cation (fi gure 2, b). In the lower part of the tooth of the diamond hone under study, after its dressing, the thickness of the left diamond-bearing layer reaches 2.9 mm and decreases to 2.7–2.6 mm towards the tooth vertex (fi gure 2, a). The thickness of the right diamond bearing layer at the same tooth height is about 2.4 mm. The diff erences in the thicknesses of the diamond-bearing layer between the hone teeth reach 50 % on average. In some photographs, cracks were found in the diamond bearing layer and in the material of the annular gear (fi gure 3 a), diamond bearing layers of a modifi ed structure formed at the site of transition from the tooth root to the main part of the hone (fi gure 3 b, c). It can be assumed that at a temperature of about 170 °C, as a result of the movement of a more mobile liquid material of the annular gear, a part of the diamond bearing layer is captured and transferred to the formed space at the level of the tooth stem. In this case, the thickness of the diamond-bearing layer may vary signifi cantly. In most of the analyzed tooth sections, there are no distortions of the diamond layer. A fairly clear boundary has been formed between the material of the annular gear and the diamond bearing layer at the tooth root. Delamination along the interface is rare and mainly occurs at the root of the hone tooth. Fig. 1. Fragment of the working surface of the hone teeth
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