Spray forming

About: Spray forming is a research topic. Over the lifetime, 1153 publications have been published within this topic receiving 12869 citations. The topic is also known as: spray casting & spray deposition.

Metal matrix composites made by spray forming

Abstract: Spray-formed metals have a finer structure, near zero segregation and improved mechanical properties resulting from rapid solidification, when compared with conventional materials. A further benefit of spray forming is that it gives greater freedom to add any second or third phase, liquid of solid, by entraining a stream of the added phase into the atomized spray before deposition. This paper shows that metals matrix composites made by spray forming can incorporate both of these benefits in one operation. A comparison with the equivalent materials made by powder metallurgy or by the melt mixing route is made.

Modeling of Porosity during Spray Forming: Part I. Effects of Processing Parameters

Abstract: In this article, a porosity model is developed based on particle packing theory, fluid mechanics, and particle thermal and dynamic behavior during spray forming. According to this model, the amount of porosity in as-deposited materials can be estimated on the basis of the average fraction of solid in the incident spray and the solid particle packing density. A porosity coefficient Φ is introduced. By using this model, the effects of deposition distance, atomization gas pressure, melt flow rate, and melt superheat on porosity are investigated. The amount of porosity demonstrates distinct V-shaped variations with the processing parameters. Finally, the optimal processing parameters for achieving low porosity are discussed on the basis of the calculated results.

A three-dimensional model of the spray forming method

Abstract: A three-dimensional model has been formulated to calculate the shape of the general preform, using vector calculus. The shape of a rod, tube, plate, or irregular preform can be calculated at given spray forming conditions. The shape of a spray-formed rod was analyzed at various spray forming conditions using the three-dimensional model. The effects of spray forming parameters, such as spray distribution parameters, angular velocity of rotation, withdrawal velocity, spray angle, and eccentric distance on rod shape, were analyzed. The most important parameters affecting the shape of rods are the spray distribution parameters and the withdrawal velocity. The dynamic evolution of rod shape with a stepwise variation of the withdrawal velocity during spray forming was investigated. The effect of a stepwise change of the withdrawal velocity was the same as that of the scanning atomizer. The calculated surface profiles were compared with those of spray-formed 7075 aluminum alloy rods prepared on a pilot scale. The calculated results for the surface profiles were in agreement with those of the spray-formed rods.

Incremental solidification and forming

Abstract: A new concept in solidification and casting technology is outlined which relates powder metallurgy, spray forming, and conventional casting. It is shown that incremental solidification can he used to make products having enhanced properties. Rapid solidification, very low porosity, zero segregation, fine grain size, and uniform distribution of a second phase can be accomplished in various combinations though, regrettably, not all together. A terminology appropriate to the new concept has been developed together with certain definitions. Basic equations are proposed to describe a general model spray forming, from which solutions can be derived in particular practical cases.