TY - THES

T1 - Structure and properties of Ti-N-B coatings deposited by thermal CVD

AU - Hochauer, David

N1 - embargoed until null

PY - 2006

Y1 - 2006

N2 - Cutting tools have to withstand different types of wear, e.g. abrasion, adhesion, diffusion, and oxidation. The deposition of hard coatings in order to increase the lifetime and the cutting performance is well-known for more than three decades. Chemical vapor deposition (CVD) is a widely used process to coat cemented carbide tools. The aim of this work is to examine the influence of boron addition to thermal CVD TiN coatings. The coatings are characterized with respect to composition, structure, hardness, and tribological behavior between 25 and 600°C. The chemical composition and the phase compostion were investigated by glow discharge optical emission spectroscopy (GDOES) and glancing angle X-ray diffractometer (GAXRD), respectively. The coating structure was characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A microhardness tester was used to measure the plastic universal hardness. Tribological investigations were conducted by ball-on-disc tests. The boron content was varied between 0 and 35 at.%. Boron doping causes grain refinement and the formation of TiB2. The hardness increases from 20 GPa for TiN to 45 GPa for 35 at.% B. At room temperature, low boron contents increase the friction coefficient and the wear rate, while high boron contents decrease both. The high-temperature friction coefficient increases with increasing boron content. The wear behavior at high temperatures is less influenced by the boron content.

AB - Cutting tools have to withstand different types of wear, e.g. abrasion, adhesion, diffusion, and oxidation. The deposition of hard coatings in order to increase the lifetime and the cutting performance is well-known for more than three decades. Chemical vapor deposition (CVD) is a widely used process to coat cemented carbide tools. The aim of this work is to examine the influence of boron addition to thermal CVD TiN coatings. The coatings are characterized with respect to composition, structure, hardness, and tribological behavior between 25 and 600°C. The chemical composition and the phase compostion were investigated by glow discharge optical emission spectroscopy (GDOES) and glancing angle X-ray diffractometer (GAXRD), respectively. The coating structure was characterized with scanning electron microscopy (SEM) and transmission electron microscopy (TEM). A microhardness tester was used to measure the plastic universal hardness. Tribological investigations were conducted by ball-on-disc tests. The boron content was varied between 0 and 35 at.%. Boron doping causes grain refinement and the formation of TiB2. The hardness increases from 20 GPa for TiN to 45 GPa for 35 at.% B. At room temperature, low boron contents increase the friction coefficient and the wear rate, while high boron contents decrease both. The high-temperature friction coefficient increases with increasing boron content. The wear behavior at high temperatures is less influenced by the boron content.

KW - Chemical Vapor Deposition (CVD) Titanbornitrid Ti-N-B Struktur Tribologie

KW - Chemical vapor deposition (CVD) Titanium boronitride Ti-N-B Structure Tribology

M3 - Diploma Thesis

ER -