The 400°C limitation to the most common nanoindenter material, diamond, is not due to diamond changing to graphite in air, which can happen above 750°C, but to the reaction of the nanoindenter with the sample, causing a change in the geometry. The nanoindentation methodology is very sensitive to a change in nanoindenter geometry, thus the typical solution for measurements above 400°C is to use a cBN nanoindenter. However, the cBN indenter that is commercially used at temperatures above 400°C is too soft for measuring hard coatings such as machine tool coatings. There is limited published research on improving nanoindentation measurements in this way. Thus, the objective of this thesis is to address whether a coated diamond could be used for nanoindentation between 400-750°C. Due to the results of early experiments PVD titanium is the focus of this thesis as it will adhere to diamond by forming a carbide interlayer, TiC. A methodology to determine the best coating based on resistance to oxidation and robustness of the coating at temperature was used, allowing the exploration of several different titanium based alloys and coating thickness. The methodology used is as follows: 1. PVD coatings of titanium and titanium based alloys TiAl, TiN, and TiAlN were oxidized at 500, 575, and 650°C. Measurements by SEM and EDS were taken after the oxidation at each temperature. Of the coatings tested, the pure titanium coating was determined to be the best coating. 2. The coating thickness of 0.25, 0.50, and 1.0 um were evaluated with the same static oxidation test applied to the different alloys. It was determined that 0.50 um was the best thickness. A duplicate 0.50 um thick sample had a cross-section machined by FIB, and was examined by STEM, HAADF and EELS. The results confirmed that TiC was being formed at the expected rate. 3. To determine whether a coated nanoindenter could be used for measurements, a nanoindenter was first calibrated, coated by PVD with 0.50 um thick titanium, and calibrated again. The results confirmed that a coated nanoindenter could be used for performing nanoindentation measurements. 4. To determine whether the titanium PVD coating would adhere to the diamond at temperature, a coated nanoindenter was used to measure fused silicon at 450°C. After each measurement, the nanoindenter was examined by SEM and EDS. The results confirmed that the titanium coating adhered to the diamond. This thesis demonstrates that a titanium PVD coating can protect a diamond nanoindenter during measurements between 400-750°C. The primary contributions are that coated diamond nanoindenters can be used for nanoindentation measurements, and that titanium PVD coated nanoindenters can be used for nanoindentation measurements between 400-750°C. Additional contributions include the testing of adhesion of titanium PVD coating to diamond between 400-750°C, and a methodology of evaluating coatings. / Thesis / Doctor of Philosophy (PhD)

Machining of Aluminum can be complicated due to large amounts of adhesion and diffusion of the aluminum onto the cutting tool, causing effects such as built-up layers and built-up edges. This leads to poor surface finishes and can significantly affect the tool life. CVD diamond coated tools have shown to be a potential solution to this problem and is tested and analyzed as such in this thesis. CVD diamond coated inserts are tested and compared to uncoated cemented carbide inserts and Polycrystalline diamond tipped inserts, in milling, turning and in refined tribological methods. The workpiece material in both the machine tests and the tribological tests is a high strength aluminum of the name Alumec 89. The machine tests were performed for 5 and 60 seconds at three cutting speeds, 600, 900 and 1200 m/min, keeping other parameters constant. The cutting inserts, the chips and the generated workpiece surface are examined using LOM, SEM and EDS. In the refined tribological testing, a pin-turning tribometer is used, with pins of uncoated and coated (CVD diamond) cemented carbide pins. These are tested at 5 and 30 seconds at 600 and 1200 m/min, applying a constant force of 10 N. In addition, a friction test was performed to measure the friction of the uncoated and the CVD diamond coated cemented carbide. Like the cutting inserts, the used pins were examined in LOM and SEM. The results show that while a large amount of built-up layer and built-up edges gather when using uncoated cemented carbide tools, only minimal amounts can be detected on CVD diamond and PCD. It has also been shown that the reason for the reduced adhesion in the case of diamond tooling materials is most likely due to the lack of chemical interactions between the diamond and the aluminum. The friction of the CVD diamond material was shown to be lower compared to the cemented carbide. The surface finish generated by the different materials, was the best in the case of PCD while the CVD generated multiple small scratches that severely reduced the surface roughness. This thesis provides some initial basic understanding of the interaction of CVD diamond coated inserts with high strength aluminum alloys.

The aim of the thesis is to design, conduct and assess an experiment seeking to look into the utility properties of recent tools manufactured by HAM-FINAL. The tools include polycrystalline diamond (PCD) and CVD diamond cutting edges. In the theoretical part, the attention is devoted to cutting materials with an emphasis on diamond materials, as well as to issues associated with the wearing of the cutting tools, requirements specified for precision of bores and tools used in the manufacture of precision bores. The paper further provides an overview of a selection of world’s leading manufacturers of PCD blanks, CVD diamond coatings, CVD diamond layers and reamers with PCD cutting edges.