Materials Science Forum Vol. 919

Abstract: Tribometry Methods are Focused on the Research of Tribological Processes. these Method Also Include Model Tests on Experimental Equipment, which Operate in Exactly-Defined Mode. Input Parameters of Tests are Transparent and Easy to Maintain Constant. Outputs Variables, which are Recorded, Represent Characteristic Parameters of Tribological Processes. Tests are Carried out on Simple Test Samples. the Aim of these Methods is to Numerically Express the Magnitude of Friction Force, Friction Moment, Respectively Determinate the Friction Coefficient. the Contribution is Focused on Determining the Friction Coefficient for Brass and Steel Test Samples. the Measurements were Realized on a Test Machine Tribotestor M`89. Size of the Sliding Velocity and Size of the Loading Force were Entered to the Tests as Input Parameters. Two Types of Oil were Used in the Experiments: Castrol Manual EP 80W and Madit PP90. the Results Obtained Show that the Friction Coefficient Value Decreases with the Increasing Normal Load for both Materials and Also for both Lubricants. Smaller Friction Coefficient Values were Achieved Using Lubricant Castrol Manual EP 80W for both Materials. the Average Values of the Friction Coefficient under the Load Conditions Ranged from 0.056 to 0.1240.

Abstract: Using optical 3D digitisation for dimensional and shape inspection of work-pieces became a trend recently. Before a 3D scanning process starts, surface of the measured part must usually be coated with a thin layer of anti-reflective material. Such surface coating can be performed by means of a wide range of products with various composition and application method. It is however important to know how the matt coating affects the quality and accuracy of digitization, what the structure and thickness of a coating are. The thickness of a coating may vary significantly from product to product and according to our research, it ranges between units and hundreds of µm. This article presents results of an extensive research of seven matt coating products commonly used in practice. The measurement was carried out on cylindrical and spherical elements using ATOS optical 3D scanner and an electron microscope. Thereafter, the measurement results were analysed to define how the applied coating product along with the material of measured object affect the work-piece dimensional properties. The ease of coating removal was evaluated in the research as well.

Abstract: This paper deals with the problem of stresses in the surface layer of materials after machining. It analyzes residual stresses as one of the factors affecting the state of the surface layer after machining. It describes the methods for measuring residual stresses and evaluates them from the point of view of suitability for industrial practice. A new method of measuring residual stresses in the surface layer of a workpiece for laboratory use has been proposed and experimentally tested. At the end of the article the options for further solutions in this area are proposed.

Abstract: The contribution is dealing with the forging die renovation by hard facing and following machining processes. Deviation of weldment are creating during all types of welding technologies. Shape deviation determining is necessary to purpose of machining and welded layers control quality. The optical scanner ATOS II TripleScan was used to evaluate a quality and deformations of hard facing layers created by fusion welding. Obtained 3D model of the die was used not only for evaluation of quality but also to use as workpiece for CAM simulation of roughing process. The usage of obtained 3D model by ATOS II TripleScan indicate a significant improvement of machining time based on CAQ technology.

Abstract: The contribution deals with is the material selection for spiroid gear. The combination of the softer material of one wheel with the harder material of the other wheel (or gear worm) is used for the trains of gears. The measurements were executed on the measurement stand comprising the machine aggregate with the spiroid drive. In Stage 1 of measurement, the spiroid gear was made of the steel gear worm and of the bronze wheel, in Stage 2 of measurements, it was made of the steel gear worm and of the plastic wheel. The efficiency was evaluated for various levels of the load moment, lubrication and material type used.

Abstract: Production of thin packaging sheets has gone through significant changes in recent years. Thickness of thin packaging sheets has decreased from 0.24mm down to 0.14 – 0.18mm due to the material saving, and the thickness of tin coating layer has decreased as well. Thin packaging sheets with the thickness lower than 0.18mm are produced with so called double reduction. Materials produced with this method possess higher strength properties and lower plastic properties. There exist several tests for examination of strength and plastic properties. Requirements of the processors of these sheets are that these tests are simple, without a complicated production of specimens, and easily repeatable. Exactly because of these reasons, the springback test is used for evaluation of double reduced packaging sheets by many processors from various countries. This contribution compares properties of double reduced thin packaging sheets obtained with the springback test, uniaxial tensile test and biaxial tensile test. Goal of this comparison is to objectify mechanical and plastic properties of packaging sheets obtained with the individual tests.

Abstract: This paper presents the results of a microscopic investigation of fractured Storz type fire hose couplings. It is part of the authors’ previous investigations on the failure mechanisms of this type of couplings. The investigations were performed using optical and scanning electron microscopy with Field Emission Gun (FED) and X-ray Energy Dispersive Spectrometer (EDS). It is shown that the AlSi5Cu1Mg casting alloy, used for the fabrication of these couplings, presents a normal microstructure. Thus, the nucleation and growth of micro-cracks in the investigated couplings are not related to the alloy’s microstructural defects and must be generated by a different process.

Abstract: The sample of a piezoelectric semi-active shunt damping material is analyzed inside an acoustic tube. The measurement of reflected and transmitted acoustic wave through the sample is realized using 4-microphone measurement method. Acoustic properties of the sample with the emphasis on acoustic transmissibility are analyzed. The composite piezoelectric sample comprising of a piezoelectric material connected to a linear shunting circuit is described, also the multimicrophone measurement methods are described in detail and the results are discussed in context of semi-active sound damping.

Abstract: Each machine and energetic equipment needs maintenance or cleaning time. Energetic equipment needs more regular cleaning so it works well and reliably, and the heat transfer is permanent and there is no energy loss. The inner surface of heating systems are successively covering during their operation, due to the chemical and physico-chemical reactions, solid, some dirt, minerals and corrosion products. It is therefore advisable to regularly clean and service these devices. The article deals with the distribution of exchangers, formation of sediments and corrosion products associated with their operation. In addition, the article describes the types of internal surface cleaning methods. The whole article ends with a chemical cleaning experiment, where the heat exchanger clogged with mineral deposits was cleaned. The defectoscopic images show how the chemical can remove all deposits and restore the exchanger flow to its original state.

Abstract: Diffusion welding is being used in aircraft, optic and electrical industry, where special alloys or combinations of metal or non-metal materials are often used. The alloys and materials come from limited sources and therefore they are expensive as well. These reasons lead to the fact that the destructive testing of diffusion bonded joints is not sufficient for the industry and the used components in operation. The paper discusses about the testing methods suitable for the diffusion bonded joints, which are commonly used in our research of diffusion welding and which are planned to be used afterwards.