Investigating the effect of the coating process on improving the quality of mechanical bonding in the casting of aluminum cylinder block with cast-in iron liner

Cast-in liner cylinder block, a crankcase with an integrated cast iron cylinder into the cylinder block, is an efficient and useful design in reducing the weight of the engine, reducing the time and cost of machining, and eliminating the environmental emission caused by the use of cast iron. The purpose of this article is to investigate the issues and challenges in the manufacturing process of this product. The most important issue in making an appropriated product is the bonding strength between the cast iron cylinder and the aluminum body, which is responsible for heat transfer between these two components. In this article, only the mechanical strength between the cast iron cylinder and the aluminum body is discussed. To achieve this goal, measures have been devised including the use of different coating methods, coating with different materials, and using different patterns such as grooves and porous casting surface (as cast) on the external surface of the cylinder to create a reliable and mechanical connection against the incoming forces caused by the piston movements and the difference is in the expansion of aluminum and cast iron components during engine operation. This study shows how a cylinder with a porous outer surface coated with zinc by melt immersion method produces a better bond quality than other tested designs concerning the bonding force of 320 N which is higher than other samples, also considering the Penetration liquid test determined that the thickness and length of cracks observed in the sample coated with zinc element is less than others.