we are going to make self-drilling screws from 1015 and 1017 wires w/ 3/16" diameter and 2 inches length. Can methanol be used as carbon source and will ther be a question of furnace safety if direct dripping into furnace is done
You cannot drip methanol in any furnace because of safety.
You have to purge the furnace with an inert gas before starting dissociation and again at the end of the process.
There are special injection furnaces for gas carburizing, with continuous control of dew point and of carbon potential. Normally you cool the parts in the furnace and then reheat to harden and temper.
Carbonitriding is a different process with different gases.