Analyzing a Critical Automotive Component with New Microscopic Tools

A typical brake pad consists of four parts: binder, reinforced fibers, friction performance modifiers, and padding. Up to 20 different raw materials may be used in the composition. While manufacturers carefully guard disclosing these formulas, a few studies have looked into brake composition such as the use of cashew nut shell liquid, reduction of copper content of brakes affecting water quality, and the surface ware of the brake.

Composite breakdown using COMPASS software

We decided to look into this ourselves with a highly useful algorithm in energy dispersive spectroscopy (EDS) on a scanning electron microscope (SEM). The software feature, called COMPASS, runs a principal component statistical analysis on the EDS spectra generated in the SEM. While most EDS systems separate the constituent parts by elements, COMPASS software pulls discrete “phases” from its EDS data. Now we can look at materials not as a disorganized grouping of elements commonly found in EDS, but as the individual components of oxides, sulfates and element-rich phases in order to better characterize complex materials. 

In our application note “Statistical Approach to EDS Analysis of an Automotive Disc Brake Pad,” one of our application scientists decided to look at a used brake pad he has taken off his 2008 Dodge Caravan. Not only did we learn about the complexity of our average automotive brake pad, but we also learned how our unique COMPASS algorithm found ten unique structures within the material. Not only was this analysis comprehensive, it only took us a few minutes to run the software. The somewhat commonplace analysis shows the utility and value of our exclusive software feature.