The amount of waste from washing dolomite aggregates increases continuously. Aggregates are washed to remove clayey pollutants.They consist of a large amount of clay minerals and carbonates. Their properties and amount depends on the type of raw material and type of washing technology. Utilization of waste from washing aggregates is common problem and has not been sought out yet. Their usage as the raw material in ceramics might be environmentally friendly way to utilize them. This paper presents technological properties, phase composition and microstructure analysis of materials made of waste sludge from washing dolomite aggregates. Research was divided into three parts: technological properties analysis, phase composition analysis and microstructure analysis. Samples made of waste dolomite sludge were formed in laboratory clay brick vacuum extruder and fired at 900, 1000 and 1100°C. For final materials, apparent density, open porosity, water absorption, compressive strength and durability were examined. Results of technological research suggest the possibility of the application of the waste sludge from washing aggregates in building ceramics technology as bricks materials. Waste sludge from washing dolomite aggregates can be used as the main raw material of building ceramics masses. Without any additional technological operations (e.g. drying or grinding), the material with satisfactory properties was obtained. According to durability results all obtained materials can be used for masonry protected against water penetration and without contact with soil and ground water and also for masonry subjected to passive exposure (F0 – according to the standard EN 771-1).
In this study, an artificial neural network application was performed to tell if 18 plates of the same material in different shapes and sizes were cracked or not. The cracks in the cracked plates were of different depth and sizes and were non-identical deformations. This ANN model was developed to detect whether the plates under test are cracked or not, when four plates have been selected randomly from among a total of 18 ones. The ANN model used in the study is a model uniquely tailored for this study, but it can be applied to all systems by changing the weight values and without changing the architecture of the model. The developed model was tested using experimental data conducted with 18 plates and the results obtained mainly correspond to this particular case. But the algorithm can be easily generalized for an arbitrary number of items.
In this study, it was achieved by using the method of impulse noise to detect internal or surface cracks that can occur in the production of ceramic plates. Ceramic materials are often used in the industry, especially as kitchenware and in areas such as the construction sector. Many different methods are used in the quality assurance processes of ceramic materials. In this study, the impact noise method was examined. This method is a test technique that was not used in applications. The method is presented as an examination technique based on whether there is a deformation on the material according to the sound coming from it as a result of a plastic bit hammer impact on the ceramic material. The application of the study was performed on plates made of ceramic materials. Here, it was made with the same type of model plates manufactured from the same material. The noise that would occur as a result of the impact applied on a point determined on the materials to be tested has been examined by the method of time-frequency analysis. The method applied gives pretty good results for distinguishing ceramic plates in good condition from those which are cracked.
In the paper, the technology of the production of the modified ceramic proppants used in the shale gas extracting process is described. The natural available materials and uncomplicated process to new ceramic proppants preparation were applied. The modification of the ceramic proppants based on the addition of the waste material as fly ash. The produced ceramic material in the form of granules characterized by high mechanical properties and low production costs. Moreover, the obtained good values of compressive strength and gas permeability for investigated proppants confirmed that this material has appropriate properties to be used in the hydraulic fracturing.
Nickel alloys belong to the group of most resistant materials when used under the extreme operating conditions, including chemically aggressive environment, high temperature, and high loads applied over a long period of time. Although in the global technology market one can find several standard cast nickel alloys, the vast majority of components operating in machines and equipment are made from alloys processed by the costly metalworking operations. Analysis of the available literature and own studies have shown that the use of casting technology in the manufacture of components from nickel alloys poses a lot of difficulty. This is due to the adverse technological properties of these alloys, like poor fluidity, high casting shrinkage, and above all, high reactivity of liquid metal with the atmospheric air over the bath and with the ceramic material of both the crucible and foundry mold. The scale of these problems increases with the expected growth of performance properties which these alloys should offer to the user. This article presents the results of studies of physico-chemical interactions that occur between theH282alloy melt and selected refractory ceramic materials commonly used in foundry. Own methodology for conducting micro-melts on a laboratory scale was elaborated and discussed. The results obtained have revealed that the alumina-based ceramics exhibits greater reactivity in contact with the H282 alloy melt than the materials based on zirconium compounds. In the conducted experiments, the ceramic materials based on zirconium silicate have proved to be a much better choice than the zirconia-silica mixture. Regardless of the type of the ceramic materials used, the time and temperature of their contact with the nickel alloy melt should always be limited to an absolutely necessary minimum required by the technological regime.
Ceramic injection moulding and gas pressure infiltration were employed for the manufacturing of alumina/AlSi10Mg composites. Porous ceramic preforms were prepared by mixing alumina powder with a multi-binder system and injection moulding of the powder polymer slurry. Then, the organic part was removed through a combination of solvent and thermal debinding, and the materials were finally sintered at different temperatures. The ceramic preforms manufactured in this way were infiltrated by an AlSi10Mg alloy. The microstructure and properties of the manufactured materials were examined using scanning electron microscopy, mercury porosimetry and bending strength testing. The results of transmission electron microscopy and scanning electron microscopy observations show that the fabricated composite materials are characterised by the percolation type of the microstructure and a lack of unfilled pores with good cohesion at the metal-ceramic interfaces. This is surprising considering that over 30% of the pores are smaller than 1 μm. The results show that the bending strength of the obtained composites decreased with increasing sintering temperature of the porous preforms.
The investigation results of the kinetics of binding ceramic moulds, in dependence on the solid phase content in the liquid ceramic slurries being 67, 68 and 69% - respectively, made on the basis of the aqueous binding agents Ludox AM and SK. The ultrasonic method was used for assessing the kinetics of strengthening of the multilayer ceramic mould. Due to this method, it is possible to determine the ceramic mould strength at individual stages of its production. Currently self-supporting moulds, which must have the relevant strength during pouring with liquid metal, are mainly produced. A few various factors influence this mould strength. One of them is the ceramic slurry viscosity, which influences a thickness of individual layers deposited on the wax model in the investment casting technology. Depositing of layers causes increasing the total mould thickness. Therefore, it is important to determine the drying time of each deposited layer in order to prevent the mould cracking due to insufficient drying of layers and thus the weakening of the multilayer mould structure.
Owing to its properties, metallic foams can be used as insulation material. Thermal properties of cast metal-ceramic composite foams have applications in transport vehicles and can act as fire resistant and acoustic insulators of bulkheads. This paper presents basic thermal properties of cast and foamed aluminum, the values of thermal conductivity coefficient of selected gases used in foaming composites and thermal capabilities of composite foams (AlSi11/SiC). A certificate of non-combustibility test of cast aluminum-ceramic foam for marine applications was included inside the paper. The composite foam was prepared by the gas injection method, consisting in direct injection of gas into liquid metal. Foams with closed and open cells were examined. The foams were foaming with foaming gas consisting of nitrogen or air. This work is one of elements of researches connected with description of properties of composite foams. In author's other works acoustic properties of these materials will be presented.
The study discusses the issues connected with the production of thin-walled ceramic slurry in the replicast cs technology. In the ceramic mould production process, a special role is played by the liquid ceramic slurry used to produce the first layer of the mould. The study examines selected technological properties of liquid ceramic slurries used to produce moulds in the replicas cs technology. The ceramic slurries for the tests were prepared based on the binders Ludox Px30 and Sizol 030, enriched with Refracourse flour. The wettability of the pattern's surface by the liquid ceramic slurry and the dependence of the apparent viscosity on the ceramic flour content in the mixture were determined. The wettability of the pattern surface by the liquid ceramic slurry was determined based on the measurement of the wetting angle. The angle was determined by means of an analysis of the computer image obtained with the use of a CDC camera.
The paper presents the use of rapid prototyping technology of three dimensional printing (3DP) to make a prototype shell casting mold. In the first step, for identification purposes, a mold was prepared to enable different alloys to be cast. All molds being cast were designed in a universal CAD environment and printed with the zp151 composite material (Calcium sulfate hemihydrate) with a zb63 binder (2- pyrrolidone). It is designated to be used to prepare colourful models presenting prototypes or casting models and molds. The usefulness of 3DP technology for use with copper alloys, aluminum and zinc was analyzed. The strength of the mold during casting was assumed as a characteristic comparative feature in the material resistance to high temperature, the quality of the resulting casting and its surface roughness. Casting tests were carried out in vacuum – pressure casting. The casting programs applied, significantly increased the quality of castings and enabled precise mold submergence. Significant improvement was noted in the quality compared to the same castings obtained by gravity casting.
This article investigates possible use of waste gypsum (synthetic), recovered via flue-gas desulfurization from coal-fired electric power plants, in foundries. Energy sector, which in Eastern Europe is mostly composed from coal-fired electric power plants, is one of the largest producers of sulfur dioxide (SO2). In order to protect the environment and reduce the amount of pollution flue-gas desulfurization (FGD) is used to remove SO2 from exhaust flue gases of fossil-fuel power plants. As a result of this process gypsum waste is produced that can be used in practical applications. Strength and permeability tests have been made and also in-depth analysis of energy consumption of production process to investigate ways of preparing the synthetic gypsum for casting moulds application. This paper also assesses the chemical composition, strength and permeability of moulds made with synthetic gypsum, in comparison with moulds made with traditional GoldStar XL gypsum and with ceramic molds. Moreover examination of structure of synthetic gypsum, the investigations on derivatograph and calculations of energy consumption during production process of synthetic gypsum in wet flue-gas desulfurization were made. After analysis of gathered data it’s possible to conclude that synthetic gypsum can be used as a material for casting mould. There is no significant decrease in key properties, and on the other hand there is many additional benefits including low energy consumption, decreased cost, and decreased environmental impact.
The new investigation method of a permeability of ceramic moulds applied in the investment casting technology, is presented in the paper. Some concepts of performing permeability measurements are shown. Investigations in which the influence of the solid phase fraction in the liquid ceramic moulding sand (LCMS) on a permeability of a multi-layer ceramic mould were performed and discussed. The permeability was estimated during two the most important stages of the technological process: in the first – after wax melting and in the second – after mould annealing. Also an influence of the matrix grain sizes (material for sprinkling) on a ceramic mould permeability was estimated.