Potassium titanate fibers are elongated crystalline structures composed of potassium and titanium. These fibers, with their high aspect ratio, are commonly employed in brake friction materials due to their ability to enhance mechanical strength, wear resistance, and dimensional stability. They also exhibit good chemical resistance and thermal stability.
However, it is important to note that fibrous potassium titanates have been identified as cancer-causing agents, leading to health concerns. These fibers fall within the size range of respirable fibers and can easily enter the body through inhalation. In Europe, there is suspicion that potassium titanate whiskers, specifically hexatitanate, may be carcinogenic, as reported by the European Chemical Agency.
Several studies were conducted on the impact of the two widely used fibrous potassium titanates in the brake industry, potassium hexatitanate and potassium octatitanate, on lung inflammatory responses. The studies confirmed that both types of fibers can cause acute lung injury, highlighting the potential carcinogenicity of potassium octatitanate due to its acicular morphology.
Consequently, the use of fibrous potassium titanates has been increasingly limited, leading to the development of non-fibrous potassium titanate alternatives. Platy forms of potassium titanates have been reported to be less harmful due to their aspect ratio. According to the International Labor Organization (ILO) and Deutsche Forschungsgemeinschaft (DFG), respirable fibers are defined as particles with a diameter ≤ 3 μm, a length ≥ 5 μm, and an aspect ratio (L/D) ≥ 3.
Innovamat has introduced a process for producing fiber-free potassium magnesium titanate with a safety aspect ratio (1 ≤ L/D ≤ 3) known as KMT24. This material falls outside the respirable fiber range.
The figure below demonstrates that KMT24 from Innovamat does not contain particles within the respirable fiber range, as the widths exceed 3 μm and the L/D ratios are maintained within the range below 3.
by Diego Chavez Jara Senior R+D+I Engineer, Friction Division