Дослідження і аналіз можливості бездифузійних фазових перетворень в поверхневому шарі деталі під дією температур шліфування

The possibility of diffusionless phase transformations in the surface layer of the ground part under the influence of instantaneous grinding temperature is investigated and analyzed. This is important because the phase Feα-Feγ transformations that may occur when grinding parts lead to the appearance of so-called grinding burns, which 2-3 times reduce the reliability and durability of the part in the working mechanism. The mechanism of phase transformations, the critical temperature of these transformations and the associated processing modes that provide this temperature are determined. This allows a reasonable approach to the definition of grinding modes and, if necessary, the application of the cooling method. In addition, the problem of optimizing grinding regimes can be solved if the processing performance is taken as a target function, and grinding temperature as a limitation. With rapid surface heating of the hardened steel part by the grinding temperature above the Ac1 line, there is a reverse martensitic transformation Feα→Feγ. The martensite range during cooling Mn-Mk to a large extent covers negative temperatures. Therefore, austenite is partially fixed in the surface layer, forming a so-called quenching burn. Dependences for determining the formation temperature for steel of any chemical composition, give the possibility to maintain the value of grinding temperature below this level during grinding. The mechanism of diffusionless reverse martensitic transformation in the high-speed surface heating by cutting grains (instantaneous temperature) is considered. The heating rate and the effect of the pressure produced by the abrasive grain on the metal during the chip removal are experimentally determined. Thus, the possibility of diffusionless phase transformation is substantiated and the dependences for the calculation of austenite formation temperatures are given, which in turn provides the opportunity to calculate safe processing regimesИсследована и проанализирована возможность бездиффузионных фазовых превращений в поверхностном слое шлифуемой детали под действием мгновенной температуры шлифования. Это важно, потому что фазовые Feα -Feγ превращения, которые могут иметь место при шлифовке деталей приводят к появлению так называемых шлифовальных прижогов, которые в 2-3 раза снижают надежность и долговечность при эксплуатации детали в работающем механизме. Определен механизм фазовых превращений, критическая температура этих превращений и связанные с этим режимы обработки, которые обеспечивают эту температуру. Это позволяет обоснованно подходить к определению режимов шлифования и, в случае необходимости, к применению способа охлаждения. Кроме того, может быть решена задача оптимизации режимов шлифования, если производительность обработки взять как целевую функцию, а как ограничение взять температуру шлифования.При быстром нагревании температурой шлифовки поверхности детали из закаленной стали выше линии АС1 имеет место обратное мартенситное превращение Feα→Feγ. Мартенситный интервал при охлаждении Мн-Мк в значительной степени охватывает отрицательные температуры. Поэтому аустенит частично фиксируется в поверхностном слое, образуя так называемый прижег закалки. Зависимости для определения температуры образования аустенита для стали любого химического состава, дают возможность при шлифовке поддерживать значение температуры шлифования ниже этого уровня. Рассмотрены механизм бездиффузионного обратного мартенситного превращения при высокоскоростном нагреве поверхности режущими зернами (мгновенной температурой). Экспериментально определена скорость нагрева и влияние давления, которое оказывает абразивное зерно на металл при снятии стружки. Таким образом обоснована возможность бездиффузионного фазового превращения и дается зависимости для расчета температур образования аустенита, что дает в свою очередь возможность рассчитать безопасные режимы обработкиДосліджено та проаналізовано можливість бездифузійних фазових перетворень в поверхневому шарі шліфованої деталі під дією миттєвої температури шліфування. Це важливо, тому що фазові Feα-Feγ перетворення, які можуть мати місце при шліфуванні деталей приводять до появи так званих шліфувальних прижогів, які в 2–3 рази знижують надійність і довговічність при експлуатації деталі в працюючому механізмі. Визначено механізм фазових перетворень, критична температура цих перетворень і пов'язані з цим режими обробки, які забезпечують цю температуру. Це дозволяє обґрунтовано підходити до визначення режимів шліфування і, в разі необхідності, до застосування методу охолодження. Крім того, може бути вирішена задача оптимізації режимів шліфування, якщо продуктивність обробки взяти як цільову функцію, а як обмеження взяти температуру шліфування.При швидкому нагріванні температурою шліфування поверхні деталі з загартованої сталі вище лінії АС1 має місце зворотне мартенситне перетворення Feα→Feγ. Мартенситний інтервал при охолодженні Мн-Мк в значній мірі охоплює негативні температури. Тому аустеніт частково фіксується в поверхневому шарі, утворюючи так званий припік гарту. Залежності для визначення температури утворення аустеніту для сталі будь-якого хімічного складу, дають можливість при шліфуванні підтримувати значення температури шліфування нижче цього рівня. Розглянуто механізм бездіффузіного зворотного мартенситного перетворення при високошвидкісному нагріванні поверхні ріжучими зернами (миттєвої температурою). Експериментально визначено швидкість нагріву і вплив тиску, яке справляє абразивне зерно на метал при знятті стружки. Таким чином обґрунтована можливість бездифузійного фазового перетворення і дається залежності для розрахунку температур утворення аустеніту, що дає в свою чергу можливість розрахувати безпечні режими обробк

Geovisualization of forest simulation modelling results: A case study of carbon sequestration and biodiversity

Sustainable forest management requires new tools to analyze spatial and temporal forest dynamics and to examine those forest parameters that are related to sustainability. We built a prototype system for data analysis and decision-making at forest enterprise level by integrating a forest ecosystem model EFIMOD-PRO (long-term prediction of forest growth and soil development) with an interactive visualization system CommonGIS for analysis of spatially and temporally related data. Using the prototype, a case study in Central European Russia simulated four silvicultural regimes over 200 years: natural development, selective forestry, legal forestry according to the Russian forestry legislation, and illegal forest practice. Exploratory analysis of the simulation results demonstrated that (1) natural stand development is the best alternative for carbon sequestration; (2) legal forest management is the best regime for timber production; (3) selective forestry combines the advantages of two previous strategies, and can be the best strategy for implementing sustainable forest management; and (4) illegal forest practices lead to a fast decrease in forest productivity and decreasing biodiversity. Interactive and dynamic visualizations with maps and statistical graphics played a crucial role in data cleaning, model validation, and analysis of simulation results. The case study demonstrated the potential of integrating forest ecosystem models with exploratory data visualization for the analysis and expert evaluation at the local level. The prototype can be used to present ecological and silvicultural consequences of various management practices to stakeholders and differing social groups, thus stimulating effective decision-making for sustainable forestry

Assessment of impact of construction materials on the ecological safety of home

The article deals with the problems of creating environmentally friendly aerial environment within residential premises. The main sources causing air pollution of urban housing are determined and classified. The origins of air pollution sources of residential premises are adopted as the classifying criterion. The sources of contamination are defined and assessed. Particular attention is paid to the choice of environmentally friendly building materials. The methodology for assessing toxicity of industrial waste used in the production of housing materials is developed to assess the comfort and environmental safety of home. The idea of creating “Residential buldings ID” containing information on the construction materials used is introduced

Future trends for the use of nanotechnogenic slurry waste in the production of special building materials

The article provides information about the main directions of the use of nanotechnogenic slurry waste, i.e. the industrial waste of Samara enterprises in the production of special building materials, namely, heat-resistant binders and concretes on their basis. It is found that nanotechnogenic wastes exert a polyfunctional impact in heat- resistant compositions (binders, mortars, concretes). High – alumina slurries are a plasticizer in heat-resistant composites on hydraulic cements. They are also a major component in the production of high- alumina binders and in the process of synthesizing phosphate binders which make it possible to obtain high-quality heat-resistant composites (mortars, coatings, concretes, impregnations)

Future trends for the use of nanotechnogenic slurry waste in the production of special building materials

The article provides information about the main directions of the use of nanotechnogenic slurry waste, i.e. the industrial waste of Samara enterprises in the production of special building materials, namely, heat-resistant binders and concretes on their basis. It is found that nanotechnogenic wastes exert a polyfunctional impact in heat- resistant compositions (binders, mortars, concretes). High – alumina slurries are a plasticizer in heat-resistant composites on hydraulic cements. They are also a major component in the production of high- alumina binders and in the process of synthesizing phosphate binders which make it possible to obtain high-quality heat-resistant composites (mortars, coatings, concretes, impregnations)

Assessment of impact of construction materials on the ecological safety of home

The article deals with the problems of creating environmentally friendly aerial environment within residential premises. The main sources causing air pollution of urban housing are determined and classified. The origins of air pollution sources of residential premises are adopted as the classifying criterion. The sources of contamination are defined and assessed. Particular attention is paid to the choice of environmentally friendly building materials. The methodology for assessing toxicity of industrial waste used in the production of housing materials is developed to assess the comfort and environmental safety of home. The idea of creating “Residential buldings ID” containing information on the construction materials used is introduced

Мартенситні перетворення в поверхневому шарі при шліфуванні деталей із загартованих сталей

The mechanism of direct and inverse martensitic transformation in the surface layer of a ground part of hardened steel under the influence of the grinding temperature was investigated. It is shown that the reverse martensitic transformation is carried out during grinding according to the martensite-perlite-austenite scheme. The possibility of high-speed tempering of martensite to perlite is shown, under the action of a contact grinding temperature, which, with a further increase in temperature, turns into austenite, forming an extremely harmful defect in the working surface –quenching burn.In the present work, it is shown that the quenching burn in the form of austenite is happened by the M–P–A diffusion mechanism. This made it possible to obtain graphical and analytical dependencies, using which it is possible to calculate the Ac1 temperature points of the formation of austenite for virtually any steel grade depending on the content of carbon and alloying elements. The latter circumstance makes it possible to create such grinding conditions (the type of abrasive, the characteristics of the wheel, the use of coolant, treatment regime), at which the austenite formation temperature is not attained and the quenching does not happen.Thus, as a result of the studies, it is possible to determine safe grinding temperatures for steels of different chemical compositions and treatment regimens that do not cause an increase in the grinding temperature above a certain level.Приведены результаты исследований механизма прямого и обратного мартенситного превращения в поверхностном слое шлифуемой детали из закаленной стали. Показано, что при шлифовании в основном имеет место обратное мартенситное превращение по схеме мартенсит – перлит –аустенит. Показана возможность скоростного отпуска мартенсита до перлита, под действием контактной температуры шлифования, который при дальнейшем повышении температуры превращается в аустенит, образуя прижёг закалкиНаведено результати досліджень механізму прямого і зворотного мартенситного перетворення в поверхневому шарі шліфований деталі із загартованої сталі. Показано, що при шліфуванні в основному має місце зворотне мартенситне перетворення за схемою мартенсит – перліт –аустеніт. Показана можливість швидкісного відпустки мартенситу до перліту, під дією контактної температури шліфування, який при подальшому підвищенні температури перетворюється в аустеніт, утворюючи припік гарт

Studying penetrating ability of alkaline flow solution of caprolactam production in flint aggregate

The study focuses on increasing the clinker formation degree of calculus types of siliceous rock. One of the ways to increase the flint aggregate strength is to saturate the surface layer of grains with alkaline ions. While calcining, this will provide formation of confining elements which are more caked than the inner layers. To preserve natural porosity inside granules and to increase density and durability of a surface layer, it is offered to process grains of dense siliceous rock before calcining them with a solution of alkaline flow of caprolactam production (AFCP). It is shown that the degree of density is determined by the soaking depth, which depends on the molecular structure of alkaline solution. The paper also demonstrates results of influence of processing conditions on soaking depth of grains with 10-15 mm fraction. The researchers studied the effect of AFCP solution concentration in the range varying from 3 to 20%. The duration of treatment ranged from 2 to 5 minutes. The research results are presented in the form of graphs. The optimal processing mode is also determined

Studying penetrating ability of alkaline flow solution of caprolactam production in flint aggregate

The study focuses on increasing the clinker formation degree of calculus types of siliceous rock. One of the ways to increase the flint aggregate strength is to saturate the surface layer of grains with alkaline ions. While calcining, this will provide formation of confining elements which are more caked than the inner layers. To preserve natural porosity inside granules and to increase density and durability of a surface layer, it is offered to process grains of dense siliceous rock before calcining them with a solution of alkaline flow of caprolactam production (AFCP). It is shown that the degree of density is determined by the soaking depth, which depends on the molecular structure of alkaline solution. The paper also demonstrates results of influence of processing conditions on soaking depth of grains with 10-15 mm fraction. The researchers studied the effect of AFCP solution concentration in the range varying from 3 to 20%. The duration of treatment ranged from 2 to 5 minutes. The research results are presented in the form of graphs. The optimal processing mode is also determined

Using the calculation method for low-melting clay assessment

Low-melting polymineral clays are widely used in building ceramics production. The properties of ceramic products depend on many factors. The paper describes properties of low-melting clay from Belebey deposit, Bashkiria. Using mathematical statistics methods, researchers make statistical analysis of grain size composition of clay raw material on Belebey brick factory and also analyze amount of sand additives and mixing moisture content. The study of general and technological properties of clay raw materials, and materials obtained from this raw material, was carried out in accordance with existing regulations using chemical, differential-thermal and non-standard methods. According to chemical analysis, non-standard assessment of clay raw materials was carried out by means of computer program "Assessment", developed at the Department of Building Materials Production and Engineering Structures. The method of calculating quantity and composition of melted material, formed in ceramic masses during firing, using known diagrams of aluminosilicate systems state is used. The assessment made it possible to determine maximum firing temperature and firing range and additives improving clinker formation. The studies show that calculation indicators are consistent with experimental data. They can be used for quick assessment of raw materials properties when changing its composition, and in adjustment of technological parameters of production