6 Cross-sectional view of surface region of sand core with surface coating H shows first coating layer; T is second coating layer; D is core body

6 Cross-sectional view of surface region of sand core with surface coating H shows first coating layer; T is second coating layer; D is core body

6 Cross-sectional view of surface region of sand core with surface coating H shows first coating layer; T is second coating layer; D is core body

6 Cross-sectional view of surface region of sand core with surface coating H shows first coating layer; T is second coating layer; D is core body