hardness

The purpose of the study was to assess the state of ecological development of rural rural areas of the amalgamated territorial communities of Zhytomyr district based on drinking water quality indicators of non-centralised water supply sources to ensure their sustainable development. It was found that the average pH value was within the current standard, which indicates an excellent environmental condition for this indicator. The average content of nitrates in drinking water, which in all the studied communities exceeded the standard by 1.4 to 3.5 times, was assessed at only one point.

Aim. Analysis of used bits revealed the effect when the tungsten carbide insert cutter was scrolling around its axis. Therefore, the task was to study the causes of this phenomenon. Hardness was measured followed by setting the hardness distribution gradient in the section of the hole, in order to evaluate the strength parameters of steel in the zone of the hole. Method. Applying a well-tested method, namely the method of successive approximations, we determined the estimate of the standard deviation and the evaluation criterion.

One of the main problems of rural residential areas is to provide the local population with quality drinking water, which is a major factor influencing their health. To solve this problem, it is necessary to implement effective measures not only at the state level but also at the regional and local levels. The main purpose of decentralization of power is to transfer the power and appropriate financial resources to the lowest levels of local self-government, which makes it possible for created amalgamated communities to use these resources to solve the priority issues.

This paper reports on usability of activated carbon obtained from areca nut shell, coconut shell, and coconut leaves as a filler to prepare NBR based composite for automobile based application. The carbon was activated by phosphoric acid (H3PO4) as dehydrating agent. The stoichiometric ratio of biomass and phosphoric acid was found to be 3:1 for the batch size of 300 g. As compared to commercially available carbon filler, the activated carbon derived from biomass waste responded better to the petrol swelling test.

In order to improve the properties of epoxy resins they are modified by the various compounds, in particular oligoesters. Compositions based on ED-20 epoxy resin and unsaturated oligoesters are structured in the presence of polyethylene polyamine (PEPA). The oligoester acts as a plasticizer that is not chemically bounded to the molecules of spatially crosslinked structure. It leads to the deterioration of their physical, mechanical and chemical properties during the working process of film based on epoxy-oligoester compositions.

The specificities of magneto-abrasive machining of cutting taps made from high-speed steel were researched. Surface roughness after cycle machining of cutting taps on the front surface is reduced to Ra=0,1µm, on the back surface to Ra=0,7—0,9µm, on the cylindrical surface — Ra=0,2— 0,4µm, depending on the conditions of basing the machined pieces during machining, surface hardness increases to 9—10GPa, radii of cutting edge rounded increases on 5–10%. It is shown, that the moment for cutting taps at tapping after MAM on 15–40% less than for unmachined taps.

Zinc oxide has numerous commercial device applications. Polycrystalline ZnO varistors, for example, are widely used in high voltage and power-related applications in industries such as microelectronics. One of the ways to control the properties of ZnO is its annealing in various environments, including oxygen, which leads to increased hardness and fracture toughness of ceramics.

Crosslinking of epoxy-oligoesteric mixtures composed of ED-20 dianic epoxy resin and TGM-3 oligoesteracrylate has been studied in the presence of dioxydiphenylpropane diglycidyl ether modified with adipic acid (DCDER). Crosslinking was carried out at room temperature and while heating at 383, 403 or 423 K using polyethylene polyamine as a hardener. The procedure of DCDER synthesis has been developed. The structural changes were controlled by determining film hardness and gel-fraction content. The chemistry of films formation was confirmed by IR-spectroscopy. 

Cross-linking of epoxy-oligomeric mixtures based on ED-20 industrial epoxy dianic resin and TGM-3 oligoesteracrylate in the presence of fluorine-containing peroxy oligomers has been studied. Oligomers used for the cross-linking have been obtained via chemical modification of peroxy derivative of ED-24 epoxy resin with alcohols-telomers by general formula HOCH2–(CF2–CF2)nH, where n is 3 or 4. The thermal stability of peroxy groups in the initial material, fluorine-containing peroxy oligomers and stability of cross-linked films have been examined using derivatographic methods.