Effect of Thickness and Permeability of Ceramic Shell Mould on In Situ Melted AZ91D Investment Casting

2013 ◽  
Vol 465-466 ◽  
pp. 1087-1092
Author(s):  
Hassan Jafari ◽  
Mohd Hasbullah Idris ◽  
Ali Ourdjini
Keyword(s):  
Surface Quality ◽  
Investment Casting ◽  
Solidification Rate ◽  
Ceramic Shell ◽  
Good Surface ◽  
Melting Technique ◽  
Shell Mould ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes

The influence of ceramic shell mould thickness and permeability on investment casting of AZ91D alloy using in-situ melting technique was investigated. AZ91D granules together with melting flux were charged into two different moulds having different thicknesses and four various permeabilities; then were heated at 650°C in order to be melted. Visual inspection and scanning electron microscopes were used to characterise the surface quality of cast samples. Thermal analysis was employed to further analyse the effect of mould thickness on cooling and solidification behaviour of molten metal. The findings of this research showed that thinner mould provided higher solidification rate, which is believed to favour in-situ melting enhancement. It enabled melting of the granules at the investigated temperature resulted in suppressing mould-metal reaction and producing cast samples with good surface quality. The results also showed that the permeability of shell mould was ineffective in suppressing mould-metal reaction.

Surface quality evaluation of hot deformed aluminum

2016 ◽  
Vol 1816 ◽  
Author(s):  
L.A. Espinosa Zúñiga ◽  
F.A. Pérez González ◽  
O. Zapata ◽  
N.F. Garza Montes de Oca ◽  
S. Haro
Keyword(s):  
Surface Quality ◽  
Solidification Rate ◽  
Surface Damage ◽  
Compression Tests ◽  
Cooling Rates ◽  
Heat Treated ◽  
Electron Microscopes ◽  
High Cooling Rates ◽  
Scanning Electron Microscopes

ABSTRACTThe surface quality of a heat treatable Al-Si-Mg alloy by means compression tests at 450°C was evaluated. Samples were obtained from an ingot with unidirectional solidification in order to obtain a microstructural gradient influenced by the cooling and solidification rate. The samples were heat treated by homogenization at 520°C for 4 hours prior to deformation by compression. Inverted optical and scanning electron microscopes were used to assess the surface damage of deformed samples.Analysis of deformed surface indicates a greater influence of microstructural refinement on hardening rate. It was found that the samples solidified at high cooling rates showed no defects, but at low cooling rates produced growth of grain size and intermetallic phases and thereby the high incidence of cracks in the surface.

scholarly journals A Novel Two-Axis Load Sensor Designed for in Situ Scratch Testing inside Scanning Electron Microscopes

Sensors ◽  
2013 ◽  
Vol 13 (2) ◽  
pp. 2552-2565 ◽  
Author(s):  
Hu Huang ◽  
Hongwei Zhao ◽  
Boda Wu ◽  
Shunguang Wan ◽  
Chengli Shi
Keyword(s):  
Scratch Testing ◽  
Load Sensor ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

Applications of In-situ Sample Preparation and Modeling of SEM-STEM Imaging

2008 ◽  
Author(s):  
R.J. Young ◽  
A. Buxbaum ◽  
B. Peterson ◽  
R. Schampers
Keyword(s):  
Sample Preparation ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Dual Beam ◽  
Transmission Electron ◽  
Scanning Transmission ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Preparation Techniques

Abstract Scanning transmission electron microscopy with scanning electron microscopes (SEM-STEM) has become increasing used in both SEM and dual-beam focused ion beam (FIB)-SEM systems. This paper describes modeling undertaken to simulate the contrast seen in such images. Such modeling provides the ability to help understand and optimize imaging conditions and also support improved sample preparation techniques.

Toughening of Ceramic Shell Mould with Rice Husk Fiber (CSm-RH) to Improve Strength Property and Mould Performance

2021 ◽  
Vol 2 (2) ◽  
Author(s):  
Noor Hasliza Kamarudin ◽  
◽  
Zawati Harun ◽  
Rosniza Hussain ◽  
Mohd Riduan Jamalludin ◽  
...  
Keyword(s):  
Rice Husk ◽  
Investment Casting ◽  
Ceramic Body ◽  
Ceramic Shell ◽  
Adhesion Properties ◽  
Ceramic Structure ◽  
Green Strength ◽  
Body Strength ◽  
Shell Mould ◽  
Casting Industry

For ages, ceramic shell mould (CSm) have been extensively applied in investment casting industry. The formation of CSm requires multiple steps of dipping, layering drying and firing stages. The later steps are very crucial as the solidification thin layer CSm that consist of loose ceramic particles easily cracks when exposed to the higher thermal effect. The inclusion of fiber or any reinforces phases is able to enhance fired ceramic body and also strengthen the green ceramic structure. Thus, the feasibility of rougher NaOH treated rice husk fiber (RHT) prior embedded into composited structure has shown a significant CSm improvement by induced a better adhesion properties and larger bonding area with brittle ceramic matrix, resulted in increased green strength (1.34 MPa) and fired body strength (4.32 MPa). Owing to the decomposed of lignin layer in CSm with untreated rice husk fiber (CSm-RHU) exhibited a higher porosity that provide a better permeation paths of air flow during molten metal pouring as increased 30 % from the standard CSm permeability, giving an enormous benefit for investment casting cooling process. Overall, the incorporation of RHT fiber in a CSm matrix of both green and fired body governed in toughening of brittle ceramic body, hence avoid failure to the casting mould.

Series in Microscopy in Materials Science: Electron Microscopy in Heterogeneous Catalysis. P.L. Gai and E.D. Boyes. Series Editors: B. Cantor, M.J. Goringe, and J.A Eades. Institute of Physics Publishing, Bristol, England; 2003, 233 pages (Hardback). ISBN 0-7503-0809-5

2003 ◽  
Vol 9 (4) ◽  
pp. 368-368
Author(s):  
Hiroyasu Saka
Keyword(s):  
Electron Microscopy ◽  
Heterogeneous Catalysis ◽  
Materials Science ◽  
The Past ◽  
Dynamic Observation ◽  
Electron Microscopes ◽  
Scanning Electron Microscopes ◽  
Scanning Electron

This book deals with in situ dynamic observation and analysis of heterogeneous catalysis using environmental cells (EC) in transmission (TEM) and scanning electron microscopes (SEM). In general, it is based on outstanding and unique works carried out by the authors themselves over the past three decades, who pioneered this key enabling area of materials science.

scholarly journals Optimization of Ceramic Shells for Contact with Reactive Alloys

2008 ◽  
Vol 587-588 ◽  
pp. 157-161 ◽  
Author(s):  
Teresa P. Duarte ◽  
Rui J.L. Neto ◽  
Rui Félix ◽  
F. Jorge Lino
Keyword(s):  
Mechanical Properties ◽  
Surface Quality ◽  
Investment Casting ◽  
Chemical Reactivity ◽  
High Surface ◽  
Casting Process ◽  
Ceramic Shell ◽  
High Surface Quality ◽  
Complex Shapes ◽  
Investment Casting Process

Companies are continuously under pressure to innovate their products and processes. In Portugal, there are already several examples of enterprises that have chosen research groups, associated to universities, to straighten collaboration seeking the development of new materials and advanced technological processes, to produce components with complex shapes, high surface quality, and others, at low cost, for continuously more demanding applications. Unfortunately, these cases are still a very small number, and many efforts have to be done to enlarge the collaboration university-companies. Ti and other reactive alloys are important groups of metals that are under intense and continuous research and development. For example, the high mechanical properties, low density, osteointegration behavior, corrosion resistance to fluids and tissues of the human body, the ability to be sterilized, and the possibility to obtain complex shapes, makes Ti a very attractive material for medical applications. The investment casting process, using lost wax or lost rapid prototyping models, allows designers a great amount of freedom and capacity to quickly produce castings of high dimensional accuracy and excellent surface quality suitable for different applications. Many of the castings obtained by this process are immediately ready for use, avoiding costly machining operations and joining processes, making the process very attractive to produce precision parts in Ti and other reactive alloys. However, the high reactivity of the Ti raises several compatibility problems with the traditional materials employed on the ceramic shells for casting steels and non ferrous alloys. The fragile surface layer obtained on the interface Ti-ceramic shell, result of the Ti reaction with oxygen and nitrogen of the shell, significantly reduces the mechanical properties of the cast parts, making them useless. The aim of the present work is the study of the interface properties of the Ti-ceramic shell, in order to be able to manufacture ceramic shells of low chemical reactivity for the investment casting process of reactive alloys, namely; titanium alloys, inconel, aluminotitanates, and others. Ceramic shells manufactured with calcium and yttria stabilized zirconia and other non reactive ceramics were employed and the metallic interface characterized in terms of microscopic and microhardness properties.

Permeable Rice Husk Fibre Shell Mould System

2013 ◽  
Vol 372 ◽  
pp. 331-335 ◽  
Author(s):  
Zawati Harun ◽  
Noor Hasliza Kamarudin ◽  
Muhamad Zaini Yunos
Keyword(s):  
Rice Husk ◽  
Investment Casting ◽  
Open Porosity ◽  
Casting Process ◽  
Casting Defects ◽  
Ceramic Shell ◽  
Volatile Elements ◽  
Shell System ◽  
Mould Filling ◽  
Shell Mould

Basically, permeability of ceramic shell mould system play an important role in minimizing the casting defects in most investment casting shell. The mould has to be sufficiently permeable to obtain complete mould filling during casting process. Mould fill can be improved by increasing the open porosity that definitely will increase permeability ceramic shell mould. The elimination of rice husk volatile elements has contributed to the increment of pore structure that provides a great deal of connected pathways through the ceramic shell which directly will increase the permeability of the ceramic shell mould during casting process. Indeed, the rice husk fibers additions increase the permeability after firing by a factor 3 compared to the standard shell mould system (without fiber) that makes its an excellent alternative in producing higher permeable ceramic shell system.

Vacuum Induction Melting and Investment Casting Technologies Tailored to Near-Gamma TiAl Alloys

2007 ◽  
Vol 539-543 ◽  
pp. 1463-1468 ◽  
Author(s):  
Antonín Dlouhý ◽  
Kateřina Dočekalová ◽  
Ladislav Zemčík
Keyword(s):  
Investment Casting ◽  
Cost Effective ◽  
Melting Process ◽  
Vacuum Induction Melting ◽  
Crucible Wall ◽  
Induction Melting ◽  
Ceramic Shell ◽  
Shell Mould ◽  
Stress States ◽  
As Stress

The present study focuses on vacuum induction melting and investment casting of neargamma TiAl intermetallic alloys. The attention is mainly given to a cost-effective melting process in which a primary alloy ingot is re-melted in a ceramic crucible and cast into a ceramic shell mould. Two types of crucibles (based on Al2O3 and Y2O3) are considered. The most detrimental reactions that govern the contamination of the molten alloy with ceramic particles were determined. Results suggest that the crucible wall attack can be considerably limited by using either the Y2O3 (with no SiO2-type binder) or Al2O3 crucibles with a suitable coating. After pouring, a mechanical interaction associated with different thermal expansions of TiAl casts and ceramic shell moulds can result in serious product damage. A simple 1D-1D model of the cooling process was formulated and the heat flow as well as stress states in the cast-mould system were numerically solved. Process parameters (melt superheat, initial mould temperature, cooling kinetics and mould composition) were optimized in order to reduce the stress in the casts. The optimized parameters delimited a processing window in which complex-shaped TiAl castings like turbocharger wheels can be fabricated.

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