THE USE OF ALUMINUM SLAG RECYCLING PRODUCTS IN INVESTMENT CASTING TECHNOLOGIES

2018 ◽  
pp. 58-71
Author(s):  
K. V. Nikitin ◽  
A. V. Sokolov ◽  
V. I. Nikitin ◽  
N. V. D’yachkov
Keyword(s):  
Investment Casting ◽  
Gas Permeability ◽  
Close Contact ◽  
Water Soluble ◽  
Silica Sand ◽  
Ceramic Mold ◽  
Aluminum Casting Alloy ◽  
Aluminum Castings ◽  
Refractory Ceramic ◽  
Secondary Refractory

The studies of fractional, chemical and phase compositions of aluminum-containing slags of different origin found that slags are multi-component systems consisting of metal and non-metal parts. The non-metal part contains water-soluble and water-insoluble components. A practical scheme for recycling aluminum-containing slags was proposed in order to isolate the water-insoluble component to be further used a secondary refractory dusting material. It was found that the secondary refractory dusting material has a positive effect on the quality of refractory ceramic molds in investment casting and the surface finish of experimental aluminum castings. This material improves the strength of refractory ceramic molds by 9 times in comparison with silica sand molds and increases gas permeability by 15 % to 33 % in comparison with fused alumina and silica sand molds, respectively. The study covers the processes used to produce refractory ceramic molds based on the secondary refractory dusting material. The mechanism of interaction between dusting material particles and suspension is theoretically justified in terms of colloid chemistry. Negatively charged aluminum hydroxide micelles appear when ceramic mold layers are formed using the secondary refractory dusting material. Interaction between differently charged Al(OH)3 and SiO2 micelles makes secondary refractory dusting material particles come in close contact with each other. The theoretically justified processes of ceramic mold layer formation with the secondary refractory dusting material make it possible to explain the reduction in the surface roughness of castings made of AK9ch aluminum casting alloy using investment casting by 3.7 times compared with standard production processes.

Modification of Ceramic Mold for Investment Casting with Silica Sand as Stucco and Nylon Addition

2015 ◽  
Vol 1112 ◽  
pp. 510-514
Author(s):  
Bondan T. Sofyan ◽  
M. Syahid ◽  
Hafid. A. Khairuddin ◽  
R. Nurdin
Keyword(s):  
Investment Casting ◽  
Hardness Test ◽  
Casting Process ◽  
Silica Sand ◽  
Bending Test ◽  
Ceramic Mold ◽  
Mold Material ◽  
Alternative Material ◽  
Microstructure Examination ◽  
Investment Casting Process

The investment casting process has increasingly been used to produce components because it has the advantage to produce high precision part. One of the obstacles in the investment casting process in Indonesia is imported ceramic mold material. However, Indonesia has the potential silica sand which can be developed as an alternative material mullite . This study aims to develop local silica sand as stucco with the addition of nylon fibers in the slurry. Characterization of the ceramic material is bending test, edge test, and porosity tests that will be compared with the ceramic mold mullite-based. Characterization also conducted on casting product of aluminum impeller turbine by hardness test, microstructure examination by optical microscopy and SEM . The results showed that strength of ceramic molds made ​​from silica sand increase due to the addition of nylon but has not reached a standard ceramic strength. Ceramic mold is able to withstand the load at the time of pouring. There is not misrun in the casting product but some porosity due to low permeability.

Numerical Simulations and Experimental Study of Hot Core Distortion Phenomenon in Aluminum Casting

Volume 3 ◽  
2004 ◽  
Author(s):  
Sayavur Bakhtiyarov ◽  
Ruel A. Overfelt ◽  
Amit Suryawanshi ◽  
Johnathon Capps
Keyword(s):  
High Temperature ◽  
Numerical Simulations ◽  
Buoyancy Force ◽  
Metal Flow ◽  
Tensile Tests ◽  
Temperature Limit ◽  
Silica Sand ◽  
Sand Core ◽  
Aluminum Castings ◽  
Cold Box

This paper presents the results of experimental and numerical studies of hot distortion phenomenon in the phenolic urethane cold box systems. Dual Pushrod Dilatometer has been used to measure a thermal expansion/contraction of phenolic urethane cold box sand core specimens at temperature range from 25° C to 800° C. The high temperature tensile tests showed that the tensile strength of the phenolic urethane cold box silica sand cores is significantly affected by the bench life, temperature and binders level. High temperature hot distortion furnace tests on cylindrical cores showed that some aluminum coatings increase the temperature limit when distortion starts, but can’t prevent it. The hot distortion test aluminum castings showed that regardless of the application of coating, the type of coating, and anti-veining additives, all cores (silica sand) with density less than the density of the molten metal (aluminum alloy) were significantly distorted. Numerical simulations of the liquid metal flow around the cylindrical sand core and analysis of dynamic forces acting on the core during fill process showed that a buoyancy force is the major contributor to the hot distortion. It is concluded that the one of the solutions in preventing the hot distortion of sand cores is increasing their weigh, which will balance the buoyancy force and will bring the resultant force to the minimum. The hot distortion test castings using zircon sand cores (both coated and non-coated) with density almost equal to the density of the molten aluminum proved our predictions, and hot distortion has been prevented.

scholarly journals Ultrastructural and biochemical analyses reveal cell wall remodelling in lichen-forming microalgae submitted to cyclic desiccation–rehydration

2019 ◽  
Vol 125 (3) ◽  
pp. 459-469 ◽  
Author(s):  
María González-Hourcade ◽  
Marcia R Braga ◽  
Eva M del Campo ◽  
Carmen Ascaso ◽  
Cristina Patiño ◽  
...  
Keyword(s):  
Cell Wall ◽  
Close Contact ◽  
Freeze Substitution ◽  
Water Soluble ◽  
Hot Water ◽  
Cell Shrinkage ◽  
Distinctive Features ◽  
Biochemical Analyses ◽  
Species Specific ◽  
Environmental Sem

Abstract Background and Aims One of the most distinctive features of desiccation-tolerant plants is their high cell wall (CW) flexibility. Most lichen microalgae can tolerate drastic dehydration–rehydration (D/R) conditions; however, their mechanisms of D/R tolerance are scarcely understood. We tested the hypothesis that D/R-tolerant microalgae would have flexible CWs due to species-specific CW ultrastructure and biochemical composition, which could be remodelled by exposure to cyclic D/R. Methods Two lichen microalgae, Trebouxia sp. TR9 (TR9, adapted to rapid D/R cycles) and Coccomyxa simplex (Csol, adapted to seasonal dry periods) were exposed to no or four cycles of desiccation [25–30 % RH (TR9) or 55–60 % RH (Csol)] and 16 h of rehydration (100 % RH). Low-temperature SEM, environmental SEM and freeze-substitution TEM were employed to visualize structural alterations induced by D/R. In addition, CWs were extracted and sequentially fractionated with hot water and KOH, and the gel permeation profile of polysaccharides was analysed in each fraction. The glycosyl composition and linkage of the main polysaccharides of each CW fraction were analysed by GC–MS. Key Results All ultrastructural analyses consistently showed that desiccation caused progressive cell shrinkage and deformation in both microalgae, which could be rapidly reversed when water availability increased. Notably, the plasma membrane of TR9 and Csol remained in close contact with the deformed CW. Exposure to D/R strongly altered the size distribution of TR9 hot-water-soluble polysaccharides, composed mainly of a β-3-linked rhamnogalactofuranan and Csol KOH-soluble β-glucans. Conclusions Cyclic D/R induces biochemical remodelling of the CW that could increase CW flexibility, allowing regulated shrinkage and expansion of D/R-tolerant microalgae.

Collapsibility Studies of MJM Acrylate Patterns for Investment Casting

2013 ◽  
Vol 330 ◽  
pp. 839-842
Author(s):  
O.M.F. Marwah ◽  
S. Sharif ◽  
M. Ibrahim ◽  
M.H. Idris
Keyword(s):  
Investment Casting ◽  
Cost Reduction ◽  
Lead Time ◽  
Casting Process ◽  
Ash Content ◽  
Ceramic Mold ◽  
Significant Cost ◽  
Volume Production ◽  
Materials Used ◽  
Significant Cost Reduction

Direct rapid investment casting (IC) is among the favorable and economical casting process due to its flexibility in fabricating any geometrical part features within a shorter lead time. Polymer based materials used in rapid prototyping (RP) technologies are exhibiting significant cost reduction for low volume production and are potentially replacing conventional wax materials as sacrificial patterns in IC process. This paper reports on the collapsibility characteristics of acrylate patterns during the burnout process for IC molds. The acrylate based patterns were fabricated by a Multijet Modelling (MJM) process with hollow internal structure. The MJM patterns were then Slurry procedure were introduced for producing toughest ceramic mould to prevent cracking occurrence. Results showed that the acrylate patterns start to decomposed gradually from the ceramic mold at 350°C and at 600°C, a total clean burnout without any residues and ash content was attained. This study shows that acrylate patterns built from RP technologies are suitable for fabricating ceramic molds and are highly potential in substituting conventional wax for IC process.

scholarly journals Effects of Post-Treatment to Improve the Surface Quality of 3D Printing Cement Mold Casting

2021 ◽  
Vol 11 (24) ◽  
pp. 11824
Author(s):  
Seung-Yeop Chun ◽  
Geumyeon Lee ◽  
Su-jin Kim ◽  
Bora Jeong ◽  
Jeehoon Shin ◽  
...  
Keyword(s):  
Surface Roughness ◽  
3D Printing ◽  
Surface Quality ◽  
Post Treatment ◽  
Silica Sand ◽  
Gas Generation ◽  
Powder Bed ◽  
Aluminum Castings ◽  
Mold Casting ◽  
Spherical Silica

Powder bed 3D printing can be applied to sandcasting mold manufacturing to ensure high quality and economy through process innovation. In this study, refractory alumina cement was used as an aqueous binder to ensure high-temperature thermal stability to minimize the addition of organic matter to reduce gas generation. In addition, spherical silica sand, the study material, was selected to a size of 30 µm to improve the casting mold resolution. To improve the surface quality through the post-treatment process, we confirmed the change in the surface roughness of the mold depending on the surface treatment of colloidal silica and the presence or absence of heat treatment, and finally made the mold through actual casting. Changes in the surface roughness and flowability of the cast body after mold post-treatment were confirmed. For aluminum castings, the shrinkage rate and surface roughness were confirmed in a box-shaped mold via gravity casting, and the flowability of the molten metal in the mold was confirmed in a hand-shaped mold. There was a change in the roughness and porosity of the mold, owing to the post-treatment, and the influence of the surface roughness and flowability of the cast body during actual casting was confirmed.

Interface reaction during titanium alloys investment casting by residue gas in ceramic mold

Rare Metals ◽  
2018 ◽  
Vol 38 (4) ◽  
pp. 327-335
Author(s):  
Ya-Meng Wei ◽  
Zhi-Gang Lu ◽  
Xin-Yi Li ◽  
Xin Guo
Keyword(s):  
Titanium Alloys ◽  
Investment Casting ◽  
Interface Reaction ◽  
Ceramic Mold

Enhancement of Porosity of the Ceramic Shell in Investment Casting Process Using Needle Coke and Camphor

2014 ◽  
Vol 592-594 ◽  
pp. 269-275 ◽  
Author(s):  
Khyati Tamta ◽  
D. Benny Karunakar
Keyword(s):  
Investment Casting ◽  
Complex Geometry ◽  
Gas Permeability ◽  
Ferrous Metal ◽  
Dimensional Accuracy ◽  
Casting Process ◽  
Ceramic Shell ◽  
Needle Coke ◽  
Thin Sections ◽  
Investment Casting Process

Investment casting process has been a widely used process for centuries. It is known for its ability to produce components of complex shapes with dimensional accuracy and excellent surface finish. Investment casting has been used to make manufacture weapons, jewellery and art castings during the ancient civilization and today it is used to manufacture engineering components. In Investment casting wax patterns are made by wax injection and then coating of the wax patterns are done by ceramic slurry, made with silica flour and binder. After dewaxing and firing molten metal is poured in the shell and solidified casting can be achieved. Investment casting can be cast any ferrous and non ferrous metal which is difficult in die casting. Finishing operations are negligible and very thin sections as.75mm can also be cast which is not possible in sand casting but there are many challenges in Investment casting. It is relatively slow process because preparation of ceramic shell consumes a lot of time, permeability of shell is very low which causes gas permeability. Incorporation of chills is very difficult. Among all these challenges gas porosity is main problem because of poor permeability, entrapment of gases due to complex geometry of the shell, reuse of scrap metal. In the present work porosity of the shell can be increase by addition of mixture of Camphor and needle coke. After firing of the shell camphor and needle coke will be burnt leaving pores for the escape of entrapped gases. Mechanical properties of the both shell will be compared with each other.

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