Electroless Ni-P Coatings: Preparation and Evaluation of Fracture Toughness and Scratch Hardness

Table 1

The chemical baths used in Ni-8%P, Ni-10%P, and Ni-1%P/Al₂O₃ coating source [5].

Constituents	Bath I (Ni-8%P)	Bath II (Ni-10%P)	Bath III (Ni-1%P/Al2O3)	Role
Nickel sulphate	34 g/l	21g/l	15 g/l	Nickel source
Sodium hypophosphite	35 g/l	24 g/l	30 g/l	Phosphorus source
Malic acid	35 g/l	—	—	Accelerator
Succinic acid	12 g/l	5 g/l	10 g/l	Accelerator
Lactic acid	—	28 g/l	50 g/l	Complexing agent
Thiourea	1 ppm	2 ppm	3 ppm	Stabilizer
Ammonium hydroxide	15 ml	15 ml	10 ml	pH controller
Alumina	—	—	5 g/l	Source
Calgon	—	—	5  g/l	Surfactant
pH	5	4	8	—
Temperature	90°C	90°C	90°C	—
Deposition rate	15 μm/h	15 μm/h	10 μm/h	—