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

The investment casting technology is one of the major methods to produce the parts of the titanium due to its low production cost. However, the high activity of titanium melt gives rise to the requirement of high chemical stability of shell materials, to avoid or decrease the interfacial reaction between the mould and the melt. In this paper, a novel BaZrO3 – coated Al2O3 shell was first introduced to the investment casting of titanium alloy. The grain size and baking temperature on the properties of the novel mould were investigated, and then the Ti6Al4V and TiNi alloys were successfully casted by means of this shell. The alloy-mould interaction was discussed. The results showed that the mould achieve high mechanical properties when the content of coarse powder was 50% after sintering 4 hours under 1500°C, and the BaZrO3 coating exhibited an effective barrier to avoid the direct contact between the mould base material and the melt, the thickness of reaction layer of TiNi alloy was about 8 μm, and 17 μm to Ti6Al4V alloy, no refractory particles and elemental diffusion were observed inside the metal. This may imply that BaZrO3 is a promising candidate material for the investment casting of titanium alloy.

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Collapsibility Studies of MJM Acrylate Patterns for Investment Casting

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.330.839 ◽

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.

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A review on alpha case formation and modeling of mass transfer during investment casting of titanium alloys

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2020.158558 ◽

2021 ◽

pp. 158558

Author(s):

Sharon Uwanyuze ◽

Janos Kanyo ◽

Sarah Myrick ◽

Stefan Schafföner

Keyword(s):

Mass Transfer ◽

Titanium Alloys ◽

Investment Casting ◽

Alpha Case

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Interface Reaction between Ti3Al-based Alloy and Oxide Mold

Materials Science Forum ◽

10.4028/www.scientific.net/msf.816.562 ◽

2015 ◽

Vol 816 ◽

pp. 562-566

Author(s):

Luo Qian

Keyword(s):

Interfacial Reaction ◽

Reaction Layer ◽

Investment Casting ◽

Interface Reaction ◽

Element Distribution ◽

Diffusion Reaction ◽

Thick Wall ◽

Mold Material ◽

Thin Wall ◽

Interfacial Reaction Layer

Ti3Al based alloys are light and high-temperature materials, having potential wide applications in the aerospace and the aeronautical industries. Molten Ti is lively, and it is easy to react with the mold material during in the investment casting, and hence to form casting defects such as α contaminated layer in the metal near the surface and gas porosity, resulting in the deterioration of the surface quality and castings mechanical properties. Therefore, the mechanism of interfacial reaction between Ti3Al-based alloys and mold is necessary to study. In this paper, the interface reaction samples of Ti-24Al-15Nb-1Mo alloy and ZrO2(Y2O3stabilized) mold were prepared by actually investment casting. Optical microscopy, SEM, EMPA and micro-hardness tests were used to study the microstructures at metal side of interface, consider the element distribution and discuss the interfacial reaction mechanism. The results show that there is interface reaction between Ti-24Al-15Nb-1Mo alloy and ZrO2(Y2O3stabilized) mold, and it belongs to the typical bilateral diffusion reaction. The elements of Zr, Y, O diffuse into molten metal, at the same time, the matrix elements spread to the oxide mold, then form interfacial reaction layer. It has been found that the interfacial reaction was not uniform in the whole interface. In the thick-wall of castings, the interfacial reaction layer was thicker, and in thin-wall, the interfacial reaction layer was thinner.

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Investment Casting of Titanium Alloys with CaO Crucible and CaZrO3Mold

Lightweight Alloys for Aerospace Application ◽

10.1002/9781118787922.ch23 ◽

2013 ◽

pp. 251-260 ◽

Cited By ~ 1

Author(s):

S.K. Kim ◽

T.K. Kim ◽

M.G. Kim ◽

T.W. Hong ◽

Y.J. Kim

Keyword(s):

Titanium Alloys ◽

Investment Casting

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Investment casting of titanium alloys with calcium zirconate moulds and crucibles

The International Journal of Advanced Manufacturing Technology ◽

10.1007/s00170-019-03538-z ◽

2019 ◽

Cited By ~ 2

Author(s):

Ulrich E. Klotz ◽

C. Legner ◽

F. Bulling ◽

L. Freitag ◽

C. Faßauer ◽

...

Keyword(s):

Titanium Alloys ◽

Investment Casting ◽

Calcium Zirconate

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Re-Melting Nb–Si-Based Ultrahigh-Temperature Alloys in Ceramic Mold Shells

Metals ◽

10.3390/met9070721 ◽

2019 ◽

Vol 9 (7) ◽

pp. 721

Author(s):

Wang ◽

Guo

Keyword(s):

Reaction Layer ◽

Interface Reaction ◽

Heating Element ◽

Ceramic Mold ◽

Face Coat ◽

Ultrahigh Temperature ◽

External Part

In furnaces with different heating elements, Nb–Si based ultrahigh-temperature alloy rods were re-melted in pure yttria mold shells and zirconia face-coat mold shells at 1850 °C for 30 min. The results evidenced that in the furnace with a tungsten heating element, the microstructure of the re-melted alloy became coarser, and the composition varied depending on the type of mold shell. Although the interface reaction layer between the re-melted alloy and the zirconia face-coat mold shell was much thicker, the deformability of the mold shell and the sand burning phenomenon of the alloy inside it were improved and ameliorated, respectively. However, after being re-melted in the furnace with a graphite heating element, the misrun phenomenon occurred in both specimens. Both re-melted alloys inside the mold shells were divided by a gap into an internal and an external part, with totally different microstructures and compositions. No reaction layer emerged at the interface between the re-melted alloy and the mold shells. Instead, infiltration zones arose in the mold shells adjacent to the interface.

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

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1112.510 ◽

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.

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