Browsing by Author "Blacksher, Corinne Haas"
Now showing 1 - 2 of 2
Results Per Page
Sort Options
Item Influence of Reactive Sputtering Process Conditions on Hardness in Transition Metal Carbide Thin Films(University of Alabama Libraries, 2024) Blacksher, Corinne Haas; Thompson, Gregory B.Transition metal carbides are increasingly popular for many coating applications because of their ultrahigh melting temperatures and high hardness. The present work reports on the role of chamber pressure and atomic mass on resulting film hardness properties in a series of different transition metal carbides that undergo reactive gas sputter deposition using ethylene as the carbon source. Varying the sputtering species (Ta, Zr, or Nb), the resulting film hardness was altered by the influence of atomic mass on the extent of atomic peening and film densification. In addition, changes in chamber pressure altered the mean free path of the sputtered atoms influencing the arrival energy during deposition. With these material and process variations, all carbide films revealed a reduction of hardness with increased pressure. Both the ZrC and NbC films had hardness values lower than their bulk values that ranged from 5 to 10 GPa over 5 to 13 mTorr; while TaC also has similar lower hardness values, these did not occur until pressures greater than approximately 7 mTorr or, in other words, the reduction in hardness with pressure was less severe. While the hardness did increase for all carbide films at 4 mTorr, it was most extreme for TaC, with a reported value near 45 GPa, making it a superhard material. At this condition, this film revealed a mixed texture of {111} and {200} indicative that the hardness of the film promoted the elastically soft cube direction formation to now become comparable to the lower surface energy close-packed planes. These effects are explained through the changes in grain sizes and film densification that occur through momentum transfer as a function of metal mass. Collectively, this gives insights into the conditions by which to tailor hardness in transition metal carbide films and coatings.Item Influence of Transition Metal Type and Sputter Deposition Conditions on the Hardness of Transition Metal Carbide Thin Films(Journal of the European Ceramic Society, 2025-07-01) Blacksher, Corinne Haas; Stubbers, Alyssa; Weinberger, Chris R. ; Thompson, Gregory B.Transition metal carbides (TMCs) are known for their ultrahigh melting temperatures and high hardness making them ideal for coating applications in extreme environments. The present work investigates the role of atomic mass and chamber pressure on the resulting film hardness for a series of Zr, Nb, and Ta TMCs that are synthesized via reactive gas sputter deposition. For all TMCs, for deposition pressures between approximately 7 – 13 mTorr, the hardness varied between 5 – 15 GPa, which is lower than their bulk values as measured from consolidated powder billets. However, at 4 mTorr, ZrC and NbC hardness rose to approximately 20 and 27 GPa, respectively, which is closer to and at their bulk values and TaC rose to a hardness near 47 GPa, which is greater than its bulk value and is within the superhard regime. These collective effects are explained through the changes in crystallite sizes, film texture, and film densification that occur because of atomic peening effects between the different transition metal atomic masses and sputtering pressures that alter the arrival energy during deposition.