Picometer-scale surface roughness measurements inside hollow glass fibres.

A differential profilometry technique is adapted to the problem of measuring the roughness of hollow glass fibres by use of immersion objectives and index-matching liquid. The technique can achieve picometer level sensitivity. Cross validation with AFM measurements is obtained through use of vitreous silica step calibration samples. Measurements on the inner surfaces of fibre-sized glass capillaries drawn from high purity suprasil F300 tubes show a sub-nanometer roughness, and the roughness power spectrum measured in the range [5 · 10(-3) m(-1) 10(-1) m(-1)] is consistent with the description of the glass surface as a superposition of frozen capillary waves. The surface roughness spectrum of two capillary tubes of differing compositions can be quantitatively distinguished.

Reduction of clinkerization temperature by using phosphogypsum.

Valorization of phosphogypsum as mineralizer in the burning of Portland cement clinker was studied in our laboratory. X-ray fluorescence, optical microscope technique and powder X-ray diffraction were then used to characterize the synthesized clinker and its raw mixture in terms of chemical composition and clinker mineralogical composition. The effects of phosphogypsum on structural and morphological properties of clinker minerals and on the presence of alite were followed by scanning electron microscopy combined with microprobe analysis. The addition of phosphogypsum to the cement raw mixture shows that the burning temperature decreases and therefore improves the production process of clinker. The addition of 10% phosphogypsum permits a complete clinkerization at low burning temperature (1200 degrees C), instead of 1470 degrees C, which increases the cement factory efficiency by 25% and extends the service life of furnace fire brick. Structural and morphological analysis of clinker produced under the new conditions show that phosphogypsum preserve perfectly the crystalline structure of silicate phases, which leads to the improvement of physical and mechanical properties of cement.