Portable Hardness Tester for Instrumental Indentation
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le Hardness Tester for Instrumental Indentation E. V. Gladkikha, b, *, I. I. Maslenikovb, V. N. Reshetovc, and A. S. Useinovb a
Moscow Institute of Physics and Technology (National Research University), Dolgoprudny, Moscow oblast, 141701 Russia b Technological Institute of Superhard and New Carbon Materials, Troitsk, Moscow oblast, 108840 Russia c National Research Nuclear University MEPhI, Moscow, 115409 Russia *e-mail: [email protected] Received October 15, 2019; revised December 25, 2019; accepted December 27, 2019
Abstract—An instrument capable of assessing the hardness of materials by instrumental indentation under industrial-production conditions, including pipelines and parts of working mechanisms (bridges, railroad tracks, ship mechanisms, and other products), which operate outdoors, is described. The key components of the device are: a load-applying element (electromagnetic actuator), a displacement sensor (a capacitive sensor mounted on the working rod) and an indenter (a Berkovich diamond tip with a diameter of 500 μm and a radius of 100 nm). The largest force that can be applied to the sample is 10 N, and the maximum movement of the indenter reaches 150 μm. For the convenience of measuring both bulk and thin samples, a portable hardness tester is equipped with two different nozzles. The main peculiar feature of the device is measurement of the hardness and the Young’s modulus of the material within a single working cycle. The device is tested on various materials: steels of grades 40Cr13 and 08Cr18N10T (including samples that underwent aging), aluminum, fused silica, polycarbonate, and laminated chipboard. The roughness of the tested surfaces and the range of loads required to carry out instrumental indentation with a portable device are determined as well. The values of the hardness and elastic modulus are consistent with data obtained by means of laboratory hardness testers. Keywords: diamond indenter, electromagnetic actuator, capacitive sensor, field conditions, elastic modulus, structural steel, nanoindentation DOI: 10.1134/S102745102003026X
INTRODUCTION Industry poses challenges to materials scientists, demanding the creation of construction materials with unique properties [1]. The development of technologies aimed at improving the functional characteristics of mechanisms and assemblies is closely related to the mechanical characteristics of materials used. For example, a decrease in the weight of some design element upon maintaining the rigidity of the product necessitates a material with high rigidity and a large Young’s modulus. For most construction materials based on different alloys there is an unambiguous relationship between hardness and strength [2, 3]. Due to this relationship, destructive strength tests can be substituted with nondestructive hardness tests. The development of materials science led to the emergence of solid, strong and light materials. Meanwhile, their properties depend to a large extent on the processing technology and can strongly vary from one batch to another
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