Carbides are a resource in Warframe that you need to rebuild your Railjack. After building your Dry Dock, and researching and building Cephalon Cy, you will then go about finding parts of the Railjack. Unfortunately, the pieces have been discarded for a long time, and require repair.
Hotfix 26.1.2 has switch things up a bit.
To repair your Railjack’s propulsion system, you will require sixty Carbides. Eximus units will drop Carbides on the Shipyard tileset on Ceres. Eximus units are rare, powerful spawns that will have an ability, similar to Warframes. They can make other units more powerful, spawn shields or fire blasts, and will have increased health and damage compared to standard enemies.
One of the best ways to find Eximus units on Ceres is by playing an endless mission. As these missions get into the later waves, around 15+, Eximus units will spawn more often. Defense missions are also a good place, as later rotations will generate more Eximus units. You can find Defense missions at Seimeni and Casta.
Carbides will also be affected by the Resource Booster that doubles your resources pickups, but we don’t know if the drops are affected by farming Warframes or Smeeta Kavata at this time. All Eximus units seem to drop between five and ten Carbides on death, however.
Now that you know where to go to get Carbides, you should be able to farm them very quickly, and get that Railjack repaired in no time.
Once you have your Railjack built, the easiest place to farm Carbides is actually Railjack missions. You can get hundreds of Carbides from completing these missions. They drop from dead enemies, glowing asteroids, containers, and red glowing mines that can be found in all the levels. If you need to farm this resource, just don’t extract when you finish a mission. Instead, travel through the level, breaking asteroids and containers with your weapons, and collecting the loot that they drop.