Refractory Sand Research Articles

Impact of Moisture Variationon Some Foundry Properties of Fori Silica Sand

Moulding Sand for metal casting is usually sourced from either natural deposit or synthetic mix of refractory sand grain binder and moisture. Each of the mix constituent is important in determining the characteristics of sand. The binding agent is responsible for bendability thereby determining the size of voids within the sand grain, while moisture level determines the plasticity of the foundry sand. Tests using American Foundry Society (AFS) Standard were followed in carrying out the experiment on Fori sand deposit to determine its suitability for foundry use. The sand was collected from the river bank of Fori, in Fori Community, Maiduguri, Borno State. The experimental test equipment includes: laboratory sand mixer, sand rammer, universal strength testing machine, permeability-meter, oven, mouldability machine, and as well as quick moisture teller. The chemical composition of the materials was carried out using atomic absorption spectrophotometer (AAS) model PG990AFG. The silica content in the material sample is about 78.65%, and with the traces of other elements, such as CaO (1.07%), Fe2O3 (0.76%), Al2O3 (15.81%), MgO (1.01%), TiO2 (2.21%), K2O (3.87%), and Na2O (1.16%), respectively. These percentages are within acceptable limits. The results of the physical properties revealed that the sand sample has clay content of 15.32% which is above the standard range of 10% - 12% recommended for natural moulding sands required for producing good quality castings. Other foundry properties of Forinatural moulding sand conducted include “moisture content” in the following ranges of percentages, 7.6%, 6.5%, 5.8%, 4.2% and 2.9% with the corresponding value of green compressive strength of (43.95, 53.47, 69.56, 68.21 and 61.16 KN/m2), dry compressive strength (93.50, 96.52, 105.50, 146.50 and 152.49 KN/m2), and permeability No. of 340, 390, 410, 430 and 440 respectively. It is clear from the test that, the lower the moisture content, the higher the dry compressive strength of the materials. The refractoriness value of the materials is 1400 ℃. The results of the physical and other foundry properties carried out show that Forisilica sand is suitable for casting non-ferrous alloys like bronze, brass and aluminium, and cast iron.

OPTIMISATION OF A RESIN-COATED CHROMITE SAND FOR RAPID SAND CASTING APPLICATIONS

Applications of three-dimensional printing (3DP) to sand casting have been well-established in the last two decades. The preferred raw material is silica (quartz) sand, as it is the most readily available and cost effective sand. However, silica sand as a refractory material has some technical limitations, including high thermal linear expansion, low refractoriness, and thermal conductivity. Therefore, it is not suitable for all castings. Other refractory sand types are available, including chromite sand, which is abundantly available in South Africa. Analysis of the physical and chemical properties of in-laboratory coating of a locally available chromite sand was conducted through known metal foundry tests that provide an understanding of the quality and suitability of the use of chromite sand as a potential substitute for silica material for rapid sand-casting applications. The results of this study will inform the industry about the optimisation of parameters for the manufacturing of a resin-coated chromite sand and its use in additive manufacturing using a Voxeljet VX 1000 printer.

ASSESSMENT OF LOCAL CHROMITE SAND AS ‘GREEN’ REFRACTORY RAW MATERIALS FOR SAND CASTING APPLICATIONS IN A POST-PANDEMIC WORLD

In a post-pandemic world, health and environmental safety will become a more important issue than it was before the COVID-19 pandemic. Several fields of engineering, including the foundry industry, have already adopted health and safety measures in the workplace. The risk of pulmonary disease caused by the inhalation of fine particles of silica sand, the main moulding material used in the foundry industry, is rampant in that industry. In terms of environmental protection, the new regulatory restrictions on the disposal of used sand create the need for moulding aggregates to be more recyclable than silica. Chromite sand is an alternative refractory sand for metal casting applications, and is abundant in South Africa. The present study investigated whether this aggregate has better overall reusability than silica. The focus of this study is on the use of chromite sand in foundries as a contribution to improving health in the workplace and to reducing the environmental impact of foundry sand.

Introducing Mesozoic siliciclastic-rich refractory sand levels based on geochemical and physical properties in Iran

This research work introduces the Early Triassic, Late Triassic-Early Jurassic, and Early Cretaceous silica-rich sand levels at east and central Alborz, Kopeh-Dagh, and Central Iran, and compares them with the Permian silica-rich sand level in the Chirouk mine at east Iran. Ghoznavi and Gheshlaq loose sand in Alborz (Early Triassic-Early Jurassic), Soh quartzite in Central Iran (Early Triassic-Early Jurassic), Firuzeh sands with mud levels in Kopeh-Dagh (Early Cretaceous), and Sarnaza in Central Alborz (Late Triassic-Early Jurassic) silica-rich levels are studied in this work. Geochemical analysis and physical factors of the studied silica levels are checked regarding grain size, heat resistance, and steel molding. The laboratory and industrial methods used for washing, sieving, heating, molding, and controlling the purity of refractory sand levels show that the main difficulty of these levels within the molding process is intra-grain cracks, which spoils the alloy’s final product. The Early Triassic level in the Ghoznavi area has a high purity but the average grain size is below the steel molding standard. The Late Triassic to Early Jurassic levels in Alborz and Central Iran are oversize with grain cracks but can be fixed by the industrial refinery methods. The size of Early Cretaceous refractory sands of Firuzeh (Kopeh-Dagh) is below the standard molding process; it can be fixed by the washing and refinery methods. The systematic exploration methods show that all the studied silica-rich sand levels have an intra-grain collapse within the molding process. Final test shows that the Chirouk silica-rich levels can be used as refractory sand for cast and molding in the steel industry.

Leishmania mortality in sand fly blood meal is not species-specific and does not result from direct effect of proteinases

BackgroundLeishmania development in sand flies is confined to the alimentary tract and is closely connected with blood meal digestion. Previously, it has been published that activities of sand fly midgut proteases are harmful to Leishmania, especially to amastigote-promastigote transition forms. However, our experiments with various Leishmania-sand fly pairs gave quite opposite results.MethodsWe evaluated the effect of semi-digested midgut content on different life stages of Leishmania donovani and Leishmania majorin vitro. Various morphological forms of parasites, including macrophage-derived amastigotes and transition forms, were incubated 2 h with midguts dissected at various intervals (6–72 h) post-blood meal or with commercially available proteinase, and their viability was determined using flow cytometry. In parallel, using amastigote-initiated experimental infections, we compared development of L. donovani in sand flies that are either susceptible (Phlebotomus argentipes and P. orientalis) or refractory (P. papatasi and Sergentomyia schwetzi) to this parasite.ResultsIn vitro, sand fly midgut homogenates affected L. major and L. donovani in a similar way; in all sand fly species, the most significant mortality effect was observed by the end of the blood meal digestion process. Surprisingly, the most susceptible Leishmania stages were promastigotes, while mortality of transforming parasites and amastigotes was significantly lower. Parasites were also susceptible to killing by rabbit blood in combination with proteinase, but resistant to proteinase itself. In vivo, L. donovani developed late-stage infections in both natural vectors; in P. argentipes the development was much faster than in P. orientalis. On the other hand, in refractory species P. papatasi and S. schwetzi, promastigotes survived activity of digestive enzymes but were lost during defecation.ConclusionsWe demonstrated that Leishmania transition forms are more resistant to the killing effect of semi-digested blood meal than 24 h-old promastigotes. Data suggest that Leishmania mortality is not caused directly by sand fly proteases, we assume that this mortality results from toxic products of blood meal digestion. Survival of L. donovani promastigotes in refractory sand flies until blood meal defecation, together with similar mortality of Leishmania parasites incubated in vitro with midgut homogenates of susceptible as well as refractory species, contradict the previously raised hypotheses about the role of midgut proteases in sand fly vector competence to Leishmania.

Surface roughness improvement of cast components in vacuum moulding by intermediate barrel finishing of fused deposition modelling patterns

In this work, investigations have been made for surface roughness (Ra) improvement of vacuum moulding (VM) components by introducing barrel finishing (BF) on fused deposition modelling patterns at preliminary stage (i.e. before being used as master patterns). The Ra improvement will help to avoid/reduce post machining/finishing operations for green manufacturing. The VM master patterns were prepared using P-430 grade acrylonitrile butadiene styrene material on commercial fused deposition modelling setup. Further, Ra of VM master pattern prepared was improved by using BF process (as intermediate process). The controllable parameters of BF and VM process (namely, media weight, cycle time, vacuum pressure and grain size of refractory sand) were studied at three levels by using Taguchi L9 orthogonal array to explore their affects on Ra of the final cast components. The results of study suggest that media weight of BF and sand grain size of VM process contribute significantly for improving Ra.

Investigation for Surface Quality Improvement of Barrel Finished FDM Patterns Based Vacuum Moulding

In this paper investigations have been made for surface quality improvement of barrel finished fused deposition modelling (FDM) pattern based vacuum moulding (VM) components. VM master pattern was prepared using p- 430 grade bs on fdm setup (uPrint-SE), whose surface finish was improved by using barrel finishing (BF) process. The controllable parameters of bf and vm process (namely: media weight, cycle time, vacuum pressure and grain size of refractory sand) were studied at three levels by using taguchi L9 orthogonal array to find out their effects on dimensional accuracy of the final casting. Aluminium 6063 alloy was used for preparing VM components.

Refractory filler sands with core–shell composite structure for the taphole nozzle in slide-gate system of steel ladles

Refractory sand used for filling the taphole nozzle in slide-gate system of steel ladle needs to form a suitable sintered crust to prevent molten metal from direct contact with the gate system which, when opened, permits flow of metal from the ladle through the taphole well. Conventional filler sand consists of powdered mixtures of at least two compositions with suitable particle size and mass ratio. We herein propose a novel core–shell-structured composite particle as the refractory sand. Silicon carbide (SiC) particles with an average diameter of 50 μm were oxidized in air at 1100–1600 °C to form SiC@SiO 2 core–shell structure. As the oxidation temperature increases, silica weight-ratio increases from 0.8 to 7.9 wt.%, equivalent to a calculated shell thickness of 20–157 nm, respectively. The crust thickness can be tailored by adjusting the shell thickness. X-ray photoelectron spectroscopy, X-ray diffractometry, and scanning electron microscopy were used to characterize the core–shell structure.

A Comparison of British and American Foundry Practice, With Special Reference to the Use of Refractory Sands. By P. G. H. Boswell. pp. viii + 106, with 4 plates and 9 text-figures. Liverpool, University Press; London, Hodder and Stoughton. 4s. 6d. net.

A Comparison of British and American Foundry Practice, With Special Reference to the Use of Refractory Sands. By P. G. H. Boswell. pp. viii + 106, with 4 plates and 9 text-figures. Liverpool, University Press; London, Hodder and Stoughton. 4<i>s</i>. 6<i>d</i>. net.

A Memoir on British Resources of Refractory Sands for Furnace and Foundry Purposes. Part I. By P. G. H. Boswell, With Chemical Analyses by H. F. Harwood and A. A. Eldridge. Pp. xii + 233. (London: Taylor and Francis, 1918) Price 8s. 6d. net.

A Memoir on British Resources of Refractory Sands for Furnace and Foundry Purposes. Part I. By P. G. H. Boswell, With Chemical Analyses by H. F. Harwood and A. A. Eldridge. Pp. xii + 233. (London: Taylor and Francis, 1918) Price 8s. 6d. net.

(1) A Memoir on British Resources of Sands and Rocks used in Glass-making, with Notes on certain Crushed Rocks and Refractory Materials (2) A Memoir on British Resources of Refractory Sands for Furnace and Foundry Purposes

IN pre-war days large quantities of Continental sands were used in both the metallurgical and glass industries, the low prices at which they were delivered at our seaboard being mainly due to their transport as ballast in returning coal-boats. Quite early in the war the stocks of these sands were exhausted, and it had become a matter of urgency to replace them by home supplies. Owing to the difficulties of transport, it was essential that, wherever possible, deposits of sand easily accessible to the industrial centres should be utilised. Much of the success which has attended the efforts to utilise our home resources of sand is unquestionably due to the survey made of them by Prof. Boswell at the instruction of the Ministry of Munitions, and in its earlier stages under the auspices of the Imperial College of Science and Technology. The author's contention that many sands were unnecessarily imported, and others equally unnecessarily moved about the country, cannot be gainsaid, and in view of the industrial importance of sands it is remarkable that hitherto there has been little or no systematic investigation of our native resources of them. (1) A Memoir on British Resources of Sands and Rocks used in Glass-making, with Notes on certain Crushed Rocks and Refractory Materials. By Prof. P. G. H. Boswell. With Chemical Analyses by Dr. H. F. Harwood and A. A. Eldridge. Second edition. Pp. xi + 183. (London: Longmans, Green, and Co., 1918.) Price 7s. 6d. net. (2) A Memoir on British Resources of Refractory Sands for Furnace and Foundry Purposes. Part i. By Prof. P. G. H. Boswell. With Chemical Analyses by Dr. H. F. Harwood and A. A. Eldridge. Pp. xii + 246. (London: Taylor and Francis, 1918.) Price 8s. 6d. net.

The properties and resources of refractory sands in this country

The properties and resources of refractory sands in this country