Titanates are widely used in friction industry. They provide high stability of friction properties so that it can be considered a hot topic. There are many types of potassium titanates and including titanates which combine potassium with other metals such as magnesium or lithium, etc. Some products are fibrous, others are made of whiskers, and others are fiber-free. The main objective of this report is to show that their final morphology can be related to their structure which in turn is related to the metal ions that alter the structure and the crystalline phase. Samples of titanates with potassium, lithium and magnesium were prepared ex-novo. X-ray diffraction of powders was used to identify the crystalline phases of the obtained titanates samples. Scanning electron microscopy was used to observe the morphology of titanates particles. Moreover, phases changes were also studied by differential thermal analysis .Several crystalline phases were found depending on the structure, the condensed formula, the metallic ion type, the ionic radius, etc. The partial substitution of Ti4+ with Li+ and Mg2+ showed that structure may change and the polymeric chains of TiO6 can be less inclined to form long particles. Titanates, and especially potassium titanates, are widely used in friction materials. This research report offers to materials engineers involved into formulas development some knowledge and tool to select the most suitable titanate to their applications. Moreover, a scientific approach to the fibrous and non-fibrous issues of titanates is discussed and needed by the friction material community. The basic unit of titanates is the octahedron with the titanium at the centre and six oxygen atoms on the corners, which tend to form polymeric chains, which in turn can form either fibrous or whisker particles. In spite of the condensed formulas, several crystalline phases may be present at the same time. The presence of metallic ions of different sizes and charge can favour the growth of particles with different shapes depending on the most favoured structure.
Marco Andreoni, Andrea Sliepecvich, Marco Cotilli, Roberto C. Dante.