• Transactions of Materials Processing
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• v.8 no.3
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• pp.289-289
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• 1999

This paper describes the investment casting of TiAl alloys. The effects of mold material and mold preheating temperature for the investment casting of TiAl on metal-mold interfacial reaction were investigated by means of optical micrography, hardness profiles and an electron probe microanalyzer. The mold materials examined were colloidal silica bonded ZrO₂, ZrSiO₄, A1₂O₃and CaO stabilized ZrO₂. When compared with conventional titanium a1loy, the high aluminum concentration of TiAl alloys helps to lower their reactivity in the molten state. The A1₂O₃mold is a promising mold material for the investment casting of TiAl in terms of the thermal stability, formability and cost. Special attention need to be paid to thermal stability and mold preheating when developing the investment calling of TiAl alloys.

• Journal of Technologic Dentistry
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• v.19 no.1
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• pp.55-61
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• 1997

To observe the difference of the special liquid influencing to the fitness of casting body among the many elements influencing to the die fitness of the casting body, we fit L/P ratio each investment, using two kinds of phosphate bonded investment, divided the density of the special liquid by 5 groups(Density 100, 75, 50, 25, 0), made 10 copying per each group and experiment 10 groups, totally 100 copying and finally we could get the result as following ; 1) In such a case of CB-30, the casting fitness of the density 100 of special liquid, group 6, was the best and in order of the density 75, 50, 25, 0 the fitness is better. 2) In such of Denti-vest, the fitness of the density 100 of the special liquid, group 1, was the best and in order of the density 75, 50, 25, 0 the fitness is better. 3) Therefore we should change the density according to the transformation of the environment as investing because of increasing the expansion of phosphate bonded investment, as increasing the density of the special liquid.

• Korean Journal of Metals and Materials
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• v.48 no.6
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• pp.551-556
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• 2010

In this report, we describe mold materials that were used to produce movable metal type by the investment casting method during the Joseon dynasty period in Korea. Samples were obtained from the Wibuinja collection, which is held by the National Museum of Korea. Most of the mold material remnants were found in the depressed areas of the movable type specimens, and we therefore performed non-destructive analyses including XRF, EDS, and XRD. Through these analyses, we were able to identify the mold remnants as hydrocerussite [trilead dihydroxide dicarbonate, $Pb_3(CO_3)_2(OH)_2$] formed in platy hexagonal crystallites. Hydrocerussite was first used to make white pigments and cosmetics in ancient Greece, but this is the first report of hydrocerussite used as mold material applied around a disposable pattern for investment casting. The results of this study will further the understanding of the production process for early movable metal type and ancient casting technologies.

• Journal of Technologic Dentistry
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• v.32 no.4
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• pp.297-305
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• 2010

Purpose: The purpose of this study was to observe the change of metal-mold reaction and surface roughness in titanium casting specimens for phosphate-silica alumina bonded investment with mold temperatures. Methods: The metal-phosphate silica alumina bonded mold interface reaction and surface roughness of titanium casting specimens according to mold temperatures were investigated. The Specimens were analysed by scanning electron microscopy and surface roughness tester. Results: The oxidation behavior indicated by the growth of oxide thickness. The titanium-oxide layer were consisted two layer of a porous external and a dense internal one. The reaction layer and surface roughness increased with increasing investment material temperature. Conclusion: In this work, The most suitable mold temperature in casting of pure titanium was $200^{\circ}C$.

• Journal of Technologic Dentistry
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• v.28 no.1
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• pp.9-17
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• 2006

The purpose of this study was to evaluate the titanium castability with a spin type casting machine(TiCast, Super R, Selec, Osaka. Japan). We tested phosphate bonded investment "Rematitan$^{(R)}$Plus(Dentaurum, Inc., Pforzheim, Germany)"of mesh grid pattern and plate pattern. Four different mold temperatures(room temperature, 200$^{\circ}C$, 400$^{\circ}C$ and 600$^{\circ}C$) were prepared for the present study. In mesh grid pattern with spruing of $\varphi$0.88㎜ dimeter, when the mold temperature increased, high percentage of castability was gained. Mold temperature showed a highly significant(p<0.05) correlation on the castability, In plate pattern, the higher the mold temperature during casting, the greater the adhesive phenomenon between Ti surface and the investment.

• Journal of Technologic Dentistry
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• v.2 no.1
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• pp.21-24
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• 1980

This experiment was intended to obtain a prefect casting body the same as the original wax patterns by melting metal into the opening of the ring. The investment ring was dried to the temperature between 600 and 700, when the wax pattern would be completely melted to leave an empty mould made in the ring. The main point to studied was the investing process for perfect casting body. This process was experimented on several important factors: the size and spatulation of investment particles, purity of wax patterns, investing time after the completion of model, and investing temperature. The results obtained from the above experiment were as follows: A desirable cast body with no fissure or pore would be mode by investing with smaller particles in the first time and with larger onces in the second, both at the temperature between 180.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.2 no.2
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• pp.53-62
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• 1979

A widely accepted indicator of a project's economic potential is the internal rate of return (IRR). The primary objective of feasibility analysis for any project is to measure the economic potential for the project, normally defined as the expected return on capital investment. The analysis should be designed to determine whether a project is technically and economically sound, and under what conditions. Therefore, there are factors other than economic potential that must be taken into account in the reasonable composition of an investment program. These kinds of factors can be given proper consideration in project selection after the economic feasibility of alternative projects has been determined. The primary reason for having to choose among different projects is that capital resources are scare : the investment budget is limited. The case project, casting facilities investment project, treated in this paper were selected for their value in illustrating the methods of feasibility analysis. This case project an actual potential project and is analyzed on the basis of the best available data for the specific conditions for that project.

• Journal of Korea Foundry Society
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• v.26 no.2
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• pp.85-91
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• 2006

Inclusions in Ti investment castings are generally known to have detrimental effects on the performance of the castings. However, actual inclusions are infrequent and hard to be located. As a result, it is extremely difficult to obtain sufficient amount of fatigue test specimens of titanium investment castings having inclusions in the gage section. Thus, in-depth research of the adverse influence of inclusions is also hindered. To address this problem, a new casting methodology of specimens containing hard alpha inclusions was developed in this study. To guarantee successful introduction of an inclusion and casting, a carefully designed mold with 8 legs and a special tool were employed. After solidification, castings were cut, and X-ray radiography determined that the inclusions were successfully incorporated into the castings. The castings were further prepared to obtain multiple test specimens and they were fatigue-tested consecutively. Fractography analysis confirmed that fatigue cracks initiated at the hard alpha inclusion. In a nonlinear regression model, the fatigue life can be modeled as an exponential function with a negative exponent of the cross-sectional area of an inclusion. The fatigue life of Ti specimens containing inclusions is inversely proportional to the cross-sectional area of an inclusion.

• Journal of Korea Foundry Society
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• v.31 no.5
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• pp.249-254
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• 2011

• Journal of Korea Foundry Society
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• v.24 no.3
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• pp.159-164
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• 2004

The aim of the present work is to investigate the possibility of in-situ synthesis and net-shape forming of the titanium matrix (TiC+TiB) hybrid composites using a casting route. From the scanning electron microscopy, electron probe micro-analyzer, X-ray diffraction and thermodynamic calculations, the spherical TiC and needle like TiB reinforced hybrid titanium matrix composites could be obtained in-situ by the conventional melting and casting route between titanium and $B_4C$. No melt-mold reaction occurred between the titanium matrix (TiC+TiB) hybrid composites and the SKK mold, since the mold is consisted with interstitial and substitutional metal-mold reaction products. Not only the sound in-situ synthesis but also the economic net-shape forming of the titanium matrix (TiC+TiB) hybrid composites could be possible by the conventional casting route.