Double Zincate Preparation Lab Report

A heating bath is used in the laboratory to allow the chemical reaction to occur at an elevated temperature around 1000C. The beaker is a glass vessel which contains the chemical solutions for the purpose of coating. It is placed in the electroless bath where the chemicals are being heated up. The glass rod is used to stir the chemical where the magnetic stirrer is not necessary. The tongs are used to lift the bath after the coating is completed. Tri-sodium citrate and thallium acetate are the chemicals used during coating process which acts as a stabilizer for the bath. It stabilizes the reaction occurring in the bath. Laboratory grade distilled water is used for the cleaning process and also to mix up with the chemicals. Nickel chloride acts

Finally, the substrate was dipped in zincate solution for 3 mins followed with cleaning process. The purpose of double zincate conversion is to improve electroless deposit adhesion on the coating surface. The step by step procedure for carrying out the zincate pre-treatment process was given in fig.1. Immediately after the zincate pre-treatment process, the substrate was carefully placed in electroless nickel phosphorous solution bath, which is readily prepared and maintained at a temperature of 850C. The composition of NiP bath along with conditions are given in table. 2. The substrate (sample A) was slowly dipped and placed on the NiP bath with desired position, so that the deposition of nickel around the surface becomes good. The temperature should be kept as constant for better reaction in between metal surfaces and solutions. The pH level was frequently checked with the aid of pH indicator paper for fine coating thickness. Whenever the coating starts a drop of SDS surfactant was plunged into the Ni-P bath exactly on the coating zone. Simultaneously nano Sic was stirred well in the separate beaker using magnetic stirrer for 1 hour. Fine stirred nano Sic was injected on to the Ni-P bath using injector with uniform time interval. After coating of the first layer (nickel phosphorous) for

Based on the weight gain of the substrate sample 8 possesses better deposition of nickel with addition of 0.1 g/ltr of SDS surfactant than other samples. Sample 6 having a weight gain of 0.12 g with 0.3 g/ltr of surfactant on Ni-P bath. Beyond this other samples possesses minor proportion of weight gain with their corresponding composition of nano Sic, SDS surfactant and temperature given in table. 4.

Table.4. Electroless coating process parameters actual values and composition 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Nano SiC (g/ltr) 0.4 0.2 0.2 0.6 0.6 0.6 0.4 0.4 0.2 0.4 0 0.2 0.4 0.6 0.8

SDS

Surfactant (g/ltr) 0.2 0.3 0.1 0.3 0.3 0.1 0.4 0.2 0.3 0 0.2 0.1 0.2 0.1 0.2

Temperature (0C) 70 65 65 75 65 65 70 60 75 70 70 75 80 75