The invention is directed to improved carbon containing refractory compositions and sintered bodies made therefrom which are particularly resistant to slag and metal erosion and to thermal shock. This is achieved by combining grains or powders of SiAION and/or silicon nitride with elemental carbon in the form of graphite, carbon black or charcoal. The particulate materials are mixed with a carbonaceous binder such as resin or pitch, pressed to shape and fired in a reducing atmosphere. Small amounts of antioxidants are also added to protect the carbon bond phase against slag attack. Additional amounts of a less expensive refractory grain or powder are also optionally added to the mix to dilute the more expensive SiAION and/or silicon nitride.