No it's not an Infantry only award. The CAR is awarded on a unit/ship basis for ground and surface action. On set Criteria and Authorized by SECNAV.
Firefights, Being subjected to sustained rocket, mortar, artillery barrage.Ship being endanger by enemy attack, Special Operations/Mine Counter Measure missions where risk of enemy fire was expected to be encountered.
The CAR is not awarded for air combat/strike missions. And award of The Purple Heart Decoration does not automatically confer award of the CAR.