The importance of foundry coating in improving the surface quality of castings cannot be over emphasized. The application of mould and core washes creates a high thermal integrity barrier between the metal and the mould resulting in the reduction of the thermal shock experienced by the sand system. These thermal shock leads to series of surface defects such as veining/finning, metal penetration, burn-on/in, scab, rat tail, erosion etc. The use of coatings reduces the tendency of occurrence of these defects. However, the understanding of the coating, its components, characteristics and mechanism of action is important. In this review, a detailed description of these topics and examples are provided where necessary. A potential area of research in foundry coating development, using sol-gel process is suggested. The application of sol-gel technology in the development of foundry coatings is a novel approach.
T. A. Burns, “The Foseco Foundryman's Hanbook,” Pergamon Press, Staffordshire, 1986.
I. D. Kascheev, N. Yu. Novozhilov, E. V. Tsarevskii, V. A. Perepelitsyn, V. A. Ryabin and N. F. Seliverstov, “Refractory Coatings for Foundry Moulds and Cores,” Journal of Refractories and Ceramics, Vol. 23, 1982, pp. 36-139.
AFS, “Moulding Methods and Materials,” 1st Edition, The Ameriacan Foundrymen’s Society, Illonois, 1962.
S. D. Chastain, “A Sand Casting Manual for the Small Foundry,” Florida, Vol. 1, 2004.
L. Horvath, “Coatings Go Beyond Appearance to Provide Quality Control,” 2010. Http://www.Foundrymag.com/Classes/Article/articledraw.Aspx.
F. W. Pursall, “Coatings for Moulds and Cores,” K. Straus, Ed., Applied Science in the Casting of Metals, Pergamon Press, Oxford, 1970.
R. E. Moore, “Refractories, Structure and Properties,” Encyclopedia of Materials: Science and Technology, 2001, pp. 8079-8099.
F. L. Pirkle, D. A. Podmeyer, “Zircon: Origin and Uses,” Society for Mining, Metallurgy and Exploration, Vol. 292. http://cam.usf.edu/CAM/exhibitions/1998_12_McCollum/supplemental_didactics/62.Zircon.pdf
J. Hlavac, “Melting Temperatures of Refractory Oxides,” Pure and Applied Chemistry, Vol. 54, No. 3, 1982, pp. 681-688. doi.org/10.1351/pac198254030681
C. E. Houssa, “Minerals in Plastics,” Bulletin de la Societe Royale des sciences de liege, Vol. 72, 2003, pp. 71-80.
J. R. Brown, “The Foseco Foundryman’s Handbook”, Pergamon Press, Oxford, 2000.
S. Derbyshire, “Coating Composition,” US patent, 4279, 946, 1981.
J. J. Horak, “Core and Mould Wash,” US patent 075, 1990.
G. D. Ulrich and D. W. Molesky, “Silica Fillers from Silicon Powder,” US patent 4,755,368,1988.
N. A. Waterman, R. Trubshaw and A. M. Pye, “Filled thermoplastic Materials Part 1: Fillers and Compounds,” International journal of Materials in Engineering Applications, Vol. 1, No. 2, 1978, pp. 74-79. doi.org/10.1016/S0141-5530(78)90036-5
K. W. Jang, W. S. Kwon, M. J. Yim and K. Paik, “Effects of Silica Filler and Diluent on Materials Properties of Non-Conductive Paste and thermal Cycling reliability of Flip Chip Assembly,” Microelectronics and packaging Society, Vol. 10, 2003, pp. 1-9.
P. L. Jain, “Principle of Foundry Technology,” 4th Edition, McGraw-Hill, New Delhi, 2006.
F.O. Traenkner, “Surface Treatments of Moulds,” US Patent 2,618,032, 1952.
J. W. G. Wells, “Olivine Uses and Beneficiation Methods,” NCSU Minerals Laboratoty Bull, Vol. 2, 1959.
M. Yekeler, U. Ulusoy and C. Hicyilmaz, “Effect of Particle Shape and Roughness of Talc Mineral Around by Different Mills on the Wettability and Floatability,” Powder Technology, Vol. 140, No. 12, 2004, pp. 68-78. doi.org/10.1016/j.powtec.2003.12.012
Z. S. A?imovi?-Pavlovi?, A. K. Prsti? and L. D. Andri?, “The Characterization of Talc-Based Coating for Application for Al-Si Alloy Casting,” Chemical Industry and Chemical Engineering Quarterly, Vol. 13, No. 1, 2007, pp. 38-40.
K. S. Ariffin, “Talc and Pyrophylite Group–2:1 Phyllosilicate,” EBS 425–Mineral Perindustria, pp. 1-21, 2000.
D. Gan, S. Lu, C. Song and Z. Wang, “Physical Properties of Poly(ether ketone ketone)/Mica Composites: Effect of Filler Content,” Materials Letters, Vol. 48, No. 5, 2001, pp. 299-302. doi.org/10.1016/S0167-577X(00)00318-9
M. Zone, “Mica,” 2010. Http://www.Mineralszone.com/minerals/mica.Html.
W. B. Parkes, “Clay-Bonded Foundry Sand,” ASP, England, 1971.
A. Astruc, E. Joliff, J. F. Chailan, E. Aragon, C. O. Petter and C. H. Sampaio, “Incorporation of Kaolin Fillers into an Epoxy/Polyamidoamine Matrix for Coatings ,” Progress in Organic Coatings, Vol. 65, No. 1, 2009, pp. 158- 168. doi.org/10.1016/j.porgcoat.2008.11.003
W. M. Bundy and J. N. Ishley, “Kaolin in paper filling and coating,” Scholars Portal Journals, Vol. 5, No. 1, 1991, pp. 397-420. doi: 10.1016/0169-1317(91)90015-2
B. W. Rowland, “Modified Clay,” US patent 2,307,239, 2006.
M. Swartzlander, “Refractory Coating: Making the Right Choice,” Modern Casting, 1992. http://www.allbusiness.com/manufacturing/fabricated-metal-product-manufacturing/340970-1.html
J. Koller and B. Schmitt, “The Challenge: Decrease the Drying Time for Wash Coatings on Sand Moulds and Cores,” The EPRI Center for Materials Production. CMP-091.
J. L. Leblane, “Rubber-Filler Interactions and Rheological Properties in Filled Compounds,” Progress in Polymer Scence, Vol. 27, No. 4, 2002, pp. 627-687. doi.org/10.1016/S0079-6700(01)00040-5
EPA “Self-Audit and Inspection Guide: Organic Finishing of Metals,” 2010. Http://www.Paintcenter.org/ctc/applimeth.Cfm.
C. J. Brinker, G. C. Frye, A. J. Hurd and C. S. Ashley, “Ashley Fundamentals of Sol-Gel Dip Coating,” Thin Solid Films, Vol. 201, No. 5, 1991, pp. 97-108. doi.org/10.1016/0040-6090(91)90158-T
A. C. Psimenos and G. Eder, “PCT-Pure Coating Technology,” 2011. http://kongre.tudoksad.org.tr/assets/Uploads/31.GunterEder-word.pdf.
S. Brannon, M. McElrath, R. Reddy and S. R. Counselor, “Navigating the Ripples of Flow Coating,” Modern Casting, pp. 29-31, 2009.
Gietech BV ir Henderieckx, “Coatings for Chemical Bounded Sand,” 2005. http://www.gietech.be/LinkClick.aspx?fileticket=l6MCLoftoMI%3D&tabid=111&mid=539
Y. P. Yakunin, G. A. Ponomarevn and E. V. Shtyrenkov, “Experience in the Preparation of Self-Drying Sand-Bur- ning Resistant Coatings for Foundry Moulds and Cores,” US Patent UDC 678.026.3.
J. Kroker, “Casting solutions,” 2010. http://www.ductile.org/magazine/2003_3/nbriefs.htm
Case Study, “Aluminium Foundry replaces TCA with Water-based Coatings,” 2010 http://www.p2pays.org/ref/05/04239.htm.
Canadian Foundry Association, “Guide to Energy Efficiency Opportunities in Canadian Foundries,” 2003. http://oee.rncan.gc.ca/cipec/ieep/newscentre/foundry/2/2_3_5.cfm?attr=29.
Cast TIP, “Controlling Refractory Coatings,” Modern Casting, 2010. http://www.thefreelibrary.com/Controlling+refractory+coatings.-a022
S. G. Baker, “Evaluating Refractory Coatings: a Practical Approach,” Modern Casting, Vol. 92, 2002, pp. 21-23.
N. Hodgkinson, “Improved Ductile Iron Casting Quality Through Optimized Coating Technology,” The Ductile Iron News, 2004. http://www.ductile.org/magazine/2004_1/coating.htm
L. Winardi and R. D. Griffin, “Effects of Coating Drying Methods on LOI, Gas Evolution and Core Permeability,”AFS Transactions Paper, Vol. 08-047, 2008.
S. N. Ramrattan and M. K. Joyce, “Final Report-Refractory Coating Control,” http://amc.aticorp.org/reports/wmu2009.pdf.
U. C. Nwaogu, T. Poulsen, R. Stage, C. Bischoff and N. S. Tiedje, “New sol-gel Refractory Coatings on Chemically-Bonded Sand Cores for Foundry Applications to Improve Casting Surface Quality,” Science and Coatings Technology, Vol. 205, No. 16, 2011. doi:10.1016/j.surfcoat.2011.02.042
J. D. Wright and N. A. J. M. Sommerdijk, “Sol-Gel Materials Chemistry and Applications,” CRC Press, London, 2001.
BAMR (Pty), “Elcometer Wet Film Combs,” 2011. http://www.bamr.co.za/elcometer%203238%20long%20edge%20wet%20film%20comb.shtml.
X. Chen, “Permeability Measurement and Numerical Modelling for Refractory Porous Materials,” AFS Transactions Paper, Vol. 08-133, 2008.
W. A. Anderson, “Permeability Relationships Using Darcy Permeability, Vacuum Decay, Pressure Decay, and Pore Size Distribution Methods on Graphitic Materials,” Carbon, Vol. 4, No. 1, 1966, pp. 107-114. doi.org/10.1016/0008-6223(66)90015-7
T. Sogabe, M. Inagaki and T. Ibuki, “Coating of graphite by polyimide and its gas permeability,” Carbon, Vol. 30, No. 3, 1992, pp. 513-516. doi.org/10.1016/0008-6223(92)90051-W
X. H. Wang and Z. Liu, “The Forchheimer Equation in Two-Dimensional Percolation Porous Media,” Physical A: Statical and Theoretical Phycics, Vol. 337, No. 3-4, 2004, pp. 384-388. doi.org/10.1016/j.physa.2004.01.047
U. M. S. Costa, J. S. Andrade Jr, H. A. Makse and H. E. Stanley, “The Role of Inertia on Fluid Flow through Disordered Porous Media,” Physical A: Statistical Mechanics and Its Applications, Vol. 266, No. 1-4, 1999, pp. 420-424. doi.org/10.1016/S0378-4371(98)00624-4
H. H. Macedo, U. M. S. Costa and M. P. Almeida, “Turbulent Effects on Fluid Flow through Disordered Porous Media,” Physical A: Statistical Mechanics and Its Applications, Vol. 299, No. 1-4, 2001, pp. 371-377. doi.org/10.1016/S0378-4371(01)00257-6
A. W. Neumann and R. J. Good, Surface and Colloid Science, Vol. 2, 1979.
Z. Lijun, W. Xuedong, L. Zeng and W. Dan, “Superhydrophobicity from Microstructured Surface,” Chinese science Bulletin, Vol. 49, No. 17, 2004, pp. 1779-1787. doi: 10.1007/bf03183400
R. Asthana and S. S. T. Mileiko, “Wettability and Interfacial Considerations in Advanced Heat-Resistant Ni-base Composites,” Bulletin of the Polish Academy of Sciences, Technical Sciences, Vol. 54, 2006.
P. Kiruthika, R. Subasri, A. Jyothirmayi, K. Sarvani and N. Y. Hebalkar, “Effect of Plasma Surface Treatment on Mechanical and Corrosion Protection Properties of UV-Curable sol-gel based GPTS-ZrO2 Coatings on Mild Steel,” Surface and Coatings Technology, Vol. 204, No. 6, 2010, pp. 1270-1276. doi.org/10.1016/j.surfcoat.2009.10.017
A. L. K. Tan, A. M. Soutar, I. F. Annergreen and Y. N. Liu, “Multilayer sol-gel Coatings for Corrosion Protection of Magnesium,” Surface and Coatings Technology, Vol. 198, No. 1-3, 2005, pp. 478-482. doi:10.1016/j.surfcoat.2004.10.066
T. Hübert, S. Svoboda and B. Oertel, “Wear Resistant Alumina Coatings Produced by a sol-gel Process,” Surface and Coatings Technology, Vol. 201, No. 1-2, 2006, pp. 487-491. doi:10.1016/j.surfcoat.2005.11.014
C. Viazzi, J. P. Bonino and F. Ansart, “Synthesis by sol-gel Route and Characterization of Yttria Stabilized Zircinia Coatings for Thermal Barrier Applications,” Surface and Coatings Technology, Vol. 201, No. 7, 2006, pp. 3889-3893. doi.org/10.1016/j.surfcoat.2006.07.241
K. H. Hass, S. Amberg-Schwab, K. Rose and G. Schottner, “Functionalized Coatings based on Inorganic-Organic Polymers (ORMOCER ?s) and Their Combination with vapor Deposited Inorganic Thin Films,” Surface and Coatings Technology, Vol. 111, No. 1, 1999, pp. 72-79. doi.org/10.1016/S0257-8972(98)00711-7
C. Guillén, A. Morales and J. Herrero, “Performance of sol-gel SiO2 Coatings onto Glass/SnO2 Superstrates,” Surface and Coating Technology, Vol. 132, No. 1, 2000, pp. 31-35. doi.org/10.1016/S0257-8972(00)00727-1
D. R. Uhlmann, T. Suratwala, J. K. Davidson, M. Boulton and G. Teowee, “Sol-gel coatings on Glass,” Journal of Non-Crystalline Solids, Vol. 318, 1997, pp. 113-122. doi.org/10.1016/S0022-3093(97)00162-2
T. B. N. Hodgkinson, “Improving Foundry Profitability through the Use of Rheotec* XL Coating,” Foseco Foundry Practice, Vol. 240, 2003.
T. Birch and D. Bell, “Improved Iron Casting Quality through Application of Advanced Coating Technology,” Foseco Foundry Practice, Vol. 243, 2005.
A. Schrey, “NORACEL* w100 - A New Technology to Prevent Veining Defects,” Foseco Foundry Practice, Vol. 246, 2007.
J. B. Laughlin, J. L. Sarquis, V. M. Jones and J. A. Cox, “Using Sol-Gel Chemistry to Synthesize a Material with properties Suited for Chemical Sensing,” Journal of Chemical Education, Vol. 77, No. 1, 2000, pp. 77-79. doi: 10.1021/ed077p77
M. Niederberger and N. Pinna, “Metal Oxide Nanoparticles in Organic Synthesis,” Formation, Assembly and Application, Vol. XIII, No. 217, 2009.
S. M. Tracey, S. N. B. Hodgson, A. K. Ray and Z. Ghassemlooy, “The Role and Interactions of Process Parameters on the Nature of Alkoxides Derived sol-gel Films,” Journal of Materials Processing Technology, Vol. 77, No. 1-3, 1998, pp. 86-94. doi.org/10.1016/S0924-0136(97)00399-3
K. Mauritz, “Sol-Gel Chemistry,” http://www.psrc.usm.edu/mauritz/solgel.html.
U. C. Nwaogu, T. Poulsen, C. Bischoff and N. S. Tiedje, “Influence of New sol-Gel Refractory Coating on the Casting Properties of Cold Box and Furan Cores for Grey Cast Iron,” The Proceedings of 69th World Foundry Congress, Hangzhou, 16-20 October 2010, pp. 648-653.