Zmiany mikrostrukturalne w płytach skał magmowych poddanych termicznej obróbce metodą płomieniowania

Abstract

Microstructural changes in flamed slabs of igneous rocks.A b s t r a c t. The investigations were carried out on stone elements (slabs) cut from 11 various igneous rocks: monzogranites, a monzodiorite, granodiorites, a syenodiorite, a labradorite and a dolerite, which were next treated by flaming. In the outer zone of the slabs, the thermally affected minerals expanded and generated among themselves compressing stress phenomena; the process finally caused brittle cracking of the grains involved. As a result, some outer rock fragments have buckled and chipped off, forming surface loss defects. The size of such defects depends on two reasons: various dimensions of rock-forming minerals in the individual slabs, and non-uniform expansion of the mineral grains involved that differ in their coefficients of thermal expansion. Eventually, the defects decide on the esthetic differentiation of the slabs after flaming. In turn, the stone zones located below the reach of flaming have been affected by cracking resulting from forces of the tensile stress. The intensity and orientation of cracks within the slabs indicate that the physico-mechanical properties of the slabs after flaming may be inferior if compared with the not flamed stone slabs.