Cerastus knights in imperial knight army

I am new to Warhammer 40k and want to build a strictly robot army. I want to get 2000 pts. I have been researching but keep seeing different answers.

My question is: if I am running a pure chaos knight or imperial knight army can I utilize 3 cerastus knights and whatever else to make the 2,000 points or can I only use 1 cerastus knight?

I know it might not be competitive but I want to run 2 lancers + 1 castigator and I think I can get 3 war glaives