Depends on your choice of precursors.. Sol-gel, thermal, sono-chemical, sputtering and many more methods to synthesize CuNP.

I would suggest simple LASER Ablation method of copper plate.. !! U may land up with higher amount of copper nanoparticles.

How do you think these particles would reduce the friction.. ?? Can you make a clear statement.

i am planning to use cu nano particles coating on the Al based cylinder liner so has to increase the life of liners & why i am planing to use cu is due to their higher thermal conductivity (heat due to friction is transferred at faster rate) and its cost is less.But i now i am thinking how to reduce the oxidation of Cu which may occur at high temperature.

One method is in attachment.

Article Copper nanoparticle modified carbon electrode for determinat...

I agree with Narasimhan Kumar in sayng that laser ablation is a good way to produce large amount of Cu NPs in a given solvent at a relatively low cost. And by the way, coating of the Al liners may be achieved by simple cold-spraying of the colloid.

However, I would suggest you to consider also possible corrosion issues in the application you are planning, being Cu a good corrosion promoter for aluminum and simple aluminum alloys. If local charging occurs during liner operation, it may lead to pitting aluminum where a contact with copper exists.