| Metal-Mold interfacial heat transfer coefficient （IHTC） is the key factor thatdetermines the accuracy of the result of CAE software, which will affect the judgmentof casting engineers. In the past several decades, lot of work relating to interfacial heattransfer has been done by investigators. In this paper, studies regarding to the heattransfer mechanism between metal-mold interface, the affecting factors and themeasuring methods of IHTC were firstly reviewed and then the shortcomings appearedin above studies were pointed out, including the lack of exploration of heat transfermechanism in tiny air-gap, the uncontrollable in the measurement of gap size and thequantization problem of IHTC.According to the shortcomings uncovered, a steady-state method with controllableair-gap and temperature for the measurement of IHTC was proposed and an apparatusfor relevant experimental study was designed. The apparatus mainly consists of fiveparts, including the metal-mold, air-gap size adjustment device, heating and temperaturecontrolling device, Data recording machine and Insulation material. By utilizing aboveapparatus, studies on the relationship between IHTC and its affecting factors, the heattransfer mechanism in tiny air-gap and quantization of IHTC were carried out. Theconclusions are drawn as follows:①For both relative large gap size （1.3mm,0.7mm） and small gap size （0.2mm）,IHTC enlarges with the rising of casting temperature. The effects of temperaturedifference on IHTC vary by gap sizes, with positive correlation in large gap size and thecontrary in small size.②IHTC decreases as the air gap increases and the smaller the gap size, the moreremarkable the influence of gap size on IHTC.③The effect of heat transfer directions on IHTC changes with different air-gapsizes. For gap size δ=1.3mm, when the temperature difference T varies between0℃and20℃, IHTC of downward heat transfer is larger than that of upward heat transfer,and when△T exceeds20℃, IHTC of downward heat transfer comes smaller. For bothδ=0.7mm and δ=0.2mm, IHTC of upward heat transfer is always larger than that ofupward heat transfer when T varies in the range of this experiment.④In air gap with tiny size, there may exist convection heat transfer, which differsfrom the traditional theories. The emerging of convection heat transfer apparently promotes the radiation heat transfer and the effect of convection on other two heattransfer strengthens along with the reducing of air gap size.⑤When δ=1.3mm, for downward heat transfer, heat conduction, taking up almost60%of total heat transfer coefficient, is the dominant way of heat transfer and heatradiation possess the remaining40%. For heat transfer with orientation of upward, heatconduction occupies50%of all heat transfer coefficient followed by heat radiationcontributing other40%, while heat convection possess only10%.⑥When δ=0.2mm, for downward heat transfer, the percent taken up byconduction and radiation is almost the same, both is about50%. For upward heattransfer, the proportion taken up by conduction reduces to45%while the proportionoccupied by convection rise to35%and the radiation is the weakest.⑦Two mathematical models with high reliability for the calculating of IHTC withheat transfer direction of upward （Eq.（1）） and downward （Eq.（2）） are put forward asfollows by applying the nonlinear regression analysis.h=0.0001*δ-0.9907*Tc2.2894*ΔT0.0092 Eq.（1）h=-420.068-30.1162δ+1.7915Tc+0.9596ΔT-1.666δ*Tc-2.673δ*ΔT-0.0014Tc*ΔT Eq.（2）+388.3144δ2+0.0007Tc2+0.0204（ΔT）2... |
