Method for ceramic electroplating a cylinder assembly of an internal combustion engine

Abstract

A method for ceramic electroplating a cylinder assembly of an internal combustion engine is provided, wherein an engine cylinder assembly's aluminum alloy based work-pieces having been inspected are chemically degreased and roughened, placed into an electroplating tank containing an electroplating solution and an additive, with blowing air for stirring the electroplating solution. After the work-pieces in the electroplating tank are suspended on cathode hook-bars, nickel plates are disposed in the anode and the right middle of the cylinder inner-wall is connected to a current auxiliary anode with a voltage, metallic ions and ceramic materials in the electroplating solution accumulate on the work-pieces and a electroplating layer is formed alternatively stacked with one metal alloy layer by one ceramic layer. The ceramic is electroplated on the surface of the aluminum alloy based work-pieces. After the work-pieces are taken out, cleaned and grinding, the parts having smooth and lubricative surfaces are gained.

1 . A method for ceramic electroplating a cylinder assembly of an internal combustion engine comprising: 
 inspecting engine cylinders of an internal combustion engine if the surface or appearance of aluminum alloy based work-pieces thereof have any defect or flaw, and eliminating the defects; arranging the inspected work-pieces in order; placing the work-pieces into a chemically degreasing sink for a degreasing operation, wherein the chemically degreasing sink contains a weak alkaline solution with concentration 10-20%, and the time of the degreasing operation is about 5-30 minutes to allow the grease becoming soluble compounds for removing; placing the chemically degreased work-pieces into a tank for cleaning by purified water; and transporting the cleaned and suspended work-pieces into a sodium hydroxide (NaOH) solution tank for roughening to make the surfaces thereof have capillarity; and then placing the roughened work-pieces into a bath containing purified water for cleaning; placing the cleaned work-pieces into a solution tank added with nitric acid HNO 3  for removing aluminum oxide on the surfaces of the work-pieces and activating the surfaces at the same time; placing the activated work-pieces a bath containing purified water for cleaning; and then zincating in which uses a chemical agent to form a film on the surface of the work-pieces for treating as a bridge for ceramic electroplating process; placing the zincated work-pieces into a bath containing purified water for cleaning; and placing the zincated work-pieces into a electroplating tank and acting as a cathode and hanging a nickel plate as anode in the electroplating tank, meanwhile, in which the electroplating solution formulated from Nickel Sulfate, Nickel Chloride and Boric acid, and an additive formulated from ceramic powder, metal alloy powder, Sodium citrate and softening agent, are added into the electroplating tank, wherein the metal alloy powder can selected based on the hardness, the hue and the likes according with the requirements of the finished product, and the softening agent can be 2-ethyl hexyl Sulfate; and 1 liter of the electroplating solution and additive is formulated from 150 g-300 g Nickel Sulfate, 25 g-60 g Nickel Chloride, 15 g-45 g Boric acid, along with 50 g-200 g ceramic powder, 5 g-50 g Sodium citrate and 5 g-30 g other metal alloy powder, with PH between 3.5 and 5; and the working temperature of the electroplating tank is in the range of 50° C.-70° C., an air tube blows air into the electroplating tank for stirring the electroplating solution and the additive sufficiently, and after the electroplating tank applies a 3V-7V voltage and a 50A-500A current, which the amount of the current is determined by the number of the work-pieces, which causes metallic ions and ceramic material in the electroplating solution to accumulate on the work-pieces and forms a electroplating layer alternatively stacked with metal alloy layers and ceramic layers, thus electroplating ceramic on the surface of the work-pieces to form ceramic parts having required thickness according with the ceramic material of a piston and a inner wall of a cylinder of a cylinder assembly of an internal combustion engine; and then connecting a right middle of the inner wall of the cylinder to a current auxiliary anode which causes ceramic electroplating layer at the right middle become uniform; transporting the parts electroplated with ceramic into a bath for cleaning with running purified water; after the cleaned parts blow-dried, taking off from suspension hooks; surface treating the blow-dried ceramic parts via grinding (such as, polishing) which makes the ceramic parts having smooth and lubricative surfaces, whereby completing finished products.