The paper discusses the problem of the choice of the moulding sand mixture composition in terms of the sand behaviour in contact with molten metal. Studies of high-temperature phenomena make assessment of the sand composition bility under real operating conditions possible, thus leading to the elimination of sand-originating casting defects. The research was conducted on selected moulding materials included in the composition of traditional moulding sand mixtures without the addition of carbon. The effect of moulding sand composition and moisture content on the linear dilatation and stress-induced allotropic changes of quartz was examined. The analysis of these phenomena was based on 3D charts and maps generated from data collected during the tests.
Machines. Technologies. Materials.
Vol. 8 (2014), Issue 1
Table of Contents
INFLUENCE OF NANOSIZED SILICON NITRIDE ADDITION DURING CASTING ON THE MICROSTRUCTURE OF X210Cr12 STEELpg(s) 35-10
The objective of this study is to investigate the effect of modification and nitrogen alloying of X210Cr12 tool steel by addition of nanosized Si N during the casting process. This is an air hardening, high-carbon, high-chromium tool steel which displays an excellent 3 4 wear resistance and has good dimensional stability and high compressive strength. Of great importance for the tools fabrication of this steel is the ledeboritic structure after casting and the influence of its characteristics on the next processes of forging. machining and heat treatment for obtaining of optimal properties. In this case a modification at the cast process and obtaining of finer structure is a precondition for better results on the next stages of tool manufacture. The role of nitrogen for obtaining of fine grained structure is already proved for many types of steels and the alloying process is precise developed. Si N is one of the most suitable nitrogenous alloying agents 3 4 for production of alloyed with nitrogen steels because of its high nitrogen content and stability. The investigations show a considerable improvement of the cast structure of X210Cr12 tool steel after the addition of small amount of nanosized silicon nitride during the casting process.
MODERN METHODS OF METAL MATRIX COMPOSITE ALLOYS PRODUCTION AND NEW APPROACHES TO REALIZATION OF REINFORCING SCHEMEpg(s) 11-13
In present work classification of known liquid-phase methods of manufacturing metal matrix composite alloys is offered. Methods of exogenous reinforcing provide input of prepared reinforcing particles in matrix melt. Methods of endogenous reinforcing provide formation of endogenous reinforcing phases directly in the melt due to flowing of controlled exothermic reactions between components of initial composite mixes. Distinctive features of interaction of phases at flowing of processes of liquid-phase high-temperature synthesis provide opportunity for realization of new conceptual approaches to realization of scheme of the reinforcing, based on combination of endogenous and exogenous reinforcing of a matrix alloy with particles of various nature and sizes.
The characteristics of types of process of liquation refining of metal melts from impurity elements is given. Efficiency of extraction- crystallization-liquation refining (ECL-process) of magnesium melts with use of additive elements is shown. The results of experimental studies on the refining of magnesium from metal impurities using additives Ti, Zr and Mn are in good agreement with the calculated data.
The highest efficiency of ECL-process of refining is achieved when cleaning of magnesium from impurities of iron by titanium additives.
General problems, which restrict wide application of aluminum matrix composite alloys (AMCA) in production sector, are discussed. Possible ways of solving the problem are recommended: using of inexpensive fillers, secondary matrix alloys; development of new methods of complex reinforcing of matrix (in-situ и ex-situ); development and updating of technological decisions about multipurpose processing of aluminum matrix composite alloys; coordination and consolidation of scientific -technical potential of scientists and engineers of Scientific-Research Institutes (SRI), Institutions of Higher Education and enterprises on the field of development and research of aluminum matrix composite alloys.
INFLUENCE OF MECHANICAL ACTIVATION OF QUARTZ SAND ON PHYSICAL AND MECHANICAL PROPERTIES OF FOUNDRY MIXTURES BY THE METHOD „NO BAKE”pg(s) 20-22
At the contemporary conditions of cast production there has been a permanent interest in economically more profitable technologies for obtaining moulds and cores of controlled properties. A part of this interest is related to quartz sands as a basic and the most common component in the practice of foundry mixture productions. State of sand surface and its influence in formation of foundry mould and core physico-chemical properties are of particular importance.
In this report, various conditions of mechanical activation on the surface of quartz sand in “a fluidized bed” are discussed. The theory of such activation necessity has been partly explained. The “time” factor in preserving the activated layer potential is noticed. The efficiency of the activated layer in producing foundry mixtures strength by the method “No Bake is shown.
As a whole, the contemporary self-hardening foundry moulds and cores represent a result of chemical reactions between quartz sands and binders at mould formation after good homogenization in mixers. Mixtures are hardened, obtaing the necessary physico-chemical characteristics; thus they realize the geometry of the future cast. One of the most important characteristics is the strength of mixtures, especially the adhesion strength that is formed on the border between sand and binding composition.
In this report, an improved method on adhesive strength determination of foundry mixtures is presented. Some theoretical protection aspects of the shown method are considered. A technological sequence of the method work and way of measurement are given. In figures, practical results from measurements of adhesion strength according to “No Bake”are shown.
Warm and hot compressive tests, bending test, measurement of density, heat capacity and thermal conductivityw ere applied to study of feature mechanical and physical properties of cast alloys Fe + (16,8 – 25,6) % Mn + (0 – 14,4) % Al + (0,02 – 2,18) % C + (0,001 – 0,135) % N.
CREATING INCENTIVES FOR TECHNOLOGICAL CHANGE: INNOVATION MANAGEMENT AND THE EU REGULATION OF ENERGY EFFICIENCYpg(s) 28-30
Тechnological innovations and change in highly regulated sectors such as the energy sector depend on decisions made by political actors in what is called a ‘joint decision system’. Such systems comprise divergently constituted actors, varying from electoral bodies to expert committees to industry representatives. The problem with decisions made in joint decisions system is that they depend more often than not on the unilateral agreement between all the participant is the decisions. The presence of veto players in areas of divergent interests creates a ‘joint decision trap’: situation where suboptimal decisions are taken. This explains why even in areas such as energy efficiency where preferences among decision makers do not vary so much as in other areas, the EU regulation, creating incentives for technological change develops rather slow.
part of the material landscape (Lemonnier 1993). It becomes part of
USE OF SCIENTIFIC APPROACHES AND METHODS FOR PERFORMANCE APPROVEMENT OF SAFETY MANAGEMENT SYSTEMS IN RAILWAYSpg(s) 31-34
Recently, the issue of safety has not been whether or not Safety Management Systems are necessary to secure a high level of operational safety in railways but if they could eventually be improved. The answer is yes and that improvement can be done on the basis of well known (and adapted to the problems of safety) scientific approaches and methods. In other words, safety understanding will be developed into a new stage – Modern Safety Management System. The present paper discusses the possibilities for the introduction of some scholarly methods into safety management in railways.
The paper deals with ways of applying mathematical methods to evaluate the result of tribodiagnostics related to vehicle combustion engines. The idea is based on a discriminative analysis that makes possible to describe one qualitative parameter (complex technical state) by means of several quantitative parameters (i.e. quantity of diagnostic parameters). The results have been verified by means of considerable statistical data of T-3-930 engines made in the Czech Republic which are used in ground vehicles.
In this article the author describes particular maintenance systems used in the past, some of which are used also at present. The basic maintenance systems include maintenance after use, preventive maintenance with predetermined intervals, and conditioned-based preventive maintenance – predictive maintenance. The current trend in the field of vehicle maintenance tend to continous monitoring of their actual status. By the help of a vehicle monitoring in use, it is possible based on current operating parameters to determinate the technical condition of the vehicle parts. Ideally to prevent the failure or damage of groups of vehicle. Tracking of vehicles in use can be effected through the telemetry. Telemetry is a technology that allows remote measurement and reporting of information.
This paper presents values comparison of friction coefficient inside ball joints depending course given by the vehicle, period of exploitation and the vehicle brand. Friction coefficient were defined on the contact surface between steel ball joint pin and the ball joint seat made from plastic covered by PTFE. For the selected working pair of the elements comparison of friction coefficient in load function are done. The preform of the measurements methodology and the test bench are additional show in the paper.