Effects of Chromium Content on Thermal Shock Cycle Resistance of (TiCr)N Hard Reactive Films

The (TiCr)N hard reactive films with 4 different Ti/Cr atomic ratios are prepared by using multi-arc ion plating. The Ti and Cr targets are used as cathodes in the co-deposition process. The high speed steel (HSS) specimens are adopted as substrate. The thermal shock cycle tests in air cooling (AC) way for the (TiCr)N films are carried out. The test temperatures are chosen as 600 °C and 700 °C, respectively. The changes of the surface compositions and morphology in the thermal shock cycle tests are investigated. The effects of Cr content in the (TiCr)N films, the temperature at which the thermal shock cycle tests are performed and the cycling times on the thermal shock resistance of the (TiCr)N films are discussed and analyzed in detail. The thermal shock behaviors of the (TiCr)N films show that the thermal shock cycling process of the (TiCr)N films consists of two stages, the steady-state oxidation stage with the increase of oxygen content at the early stage of thermal cycles, and, the instable oxidation stage with the oxidation aggravation and the occurrence of the surface cracks. The simple increase of Cr content in the (TiCr)N film does not improve the thermal shock resistance of the (TiCr)N films but easy to aggravate the surface oxidation process during the thermal shock cycles.

Download Full-text

Microstructure and Mechanical Properties of (TiAlNb)N Films

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.915-916.812 ◽

2014 ◽

Vol 915-916 ◽

pp. 812-815 ◽

Cited By ~ 1

Author(s):

Li Yan Yin ◽

Jun Zhang

Keyword(s):

Mechanical Properties ◽

Thermal Shock ◽

Bias Voltage ◽

Thermal Shock Resistance ◽

High Speed ◽

High Speed Steel ◽

Fracture Morphology ◽

X Ray Diffraction ◽

Shock Resistance ◽

Electronic Microscope

(TiAlNb)N hard reactive films are prepared by multi-arc ion plating technology using the combination of Ti-50Al (at%) and Ti-25Nb (at%) alloy targets. The high speed steel (HSS) is adopted as substrate. The surface and cross-fracture morphology, the surface compositions and the phase structures of the as-deposited (TiAlNb)N films are observed and measured by scan electronic microscope (SEM) and X-ray diffraction (XRD). The mechanical properties including the micro-hardness, the adhesion between film and substrate, the thermal shock resistance of the as-deposited (TiAlNb)N films are systemically investigated. The effects of deposition bias voltage and the addition of Nb element on the as-deposited (TiAlNb)N films are discussed. The optimally comprehensive performances, especially hardness and thermal shock resistance, exhibited by (TiAlNb)N films with bias voltage of 100V.

Download Full-text

Effect of Pre-Oxidation Treatment on the Thermal Shock Resistance of Thermal Barrier Coatings in a Combustion Gas Environment

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.1924 ◽

2010 ◽

Vol 654-656 ◽

pp. 1924-1927 ◽

Cited By ~ 3

Author(s):

Hui Mei ◽

Lai Fei Cheng ◽

Ya Nan Liu ◽

Li Tong Zhang

Keyword(s):

Thermal Shock ◽

Thermal Barrier Coatings ◽

Thermal Shock Resistance ◽

High Speed ◽

Thermal Barrier ◽

Air Plasma ◽

Oxidation Treatment ◽

Barrier Coatings ◽

Combustion Gas ◽

Shock Resistance

Thermal barrier coatings (TBCs) were deposited by an Air Plasma Spraying (APS) technique. The TBC coating comprised of 92 wt.% ZrO2 and 8 wt.% Y2O3 (YSZ), CoNiCrAlY bond coat, and MarM247 nickel base super alloy. After APS of YSZ two batches of TBC specimens were tested, one batch of which was pre-oxidised in air for 10h at 1080 oC. Both types of the specimens were directly pushed into a combustion gas at 1150 oC for 25 min and then out to the natural air for quenching. The combustion gas was produced by burning jet fuel with high speed air in a high temperature wind tunnel, which simulates the real service conditions in an aeroengine. Results show that TBCs prepared by the APS had good thermal shock resistance in the combustion gas. The pre-oxidation treatment of the TBC had a significant effect on its thermal shock life. The as-oxidised TBCs always had worse thermal shock resistance than the as-sprayed ones after thermal shock cycles.

Download Full-text

Preliminary Electron Microscopic Study of Thermal-Shock-Resistant Ceramic-Metal Composites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100097351 ◽

1981 ◽

Vol 39 ◽

pp. 140-141

Author(s):

R. J. Lauf ◽

C. S. Morgan

Keyword(s):

Grain Size ◽

Thermal Shock ◽

Thermal Shock Resistance ◽

Hot Water ◽

Alumina Powder ◽

Air Cooling ◽

Metal Composites ◽

Electrical Insulator ◽

Platinum Particles ◽

Shock Resistance

Ceramic-metal composites, or cermets, are used for a variety of applications. In general, the ceramic phase provides hardness or wear resistance while a continuous metal phase acts as a binder and provides toughness. The alumina-based cermets described here are unique in that the metallic phase (platinum) is discontinuous and constitutes only about 1 to 2 vol % of the structure. This material was developed to serve as a high-temperature electrical insulator under conditions of severe thermal shock. Because of the small grain sizes involved, electron microscopy was used to study the relation between properties and process variables as well as to better understand the mechanism of thermal shock resistance.Platinum was intimately mixed with alumina powder by precipitation from a PtCl4 solution followed by drying. The resulting powder mixture was hot-pressed in a graphite die at 1610°C for 15 min under 69 MPa (10,000 psi) pressure. Cermets produced from Alcoa A-17 alumina powder had a final grain size of 15 ± 4 μm, while Fisher Scientific reagent-grade alumina resulted in a grain size of 4 ± 1 μm. The platinum particles ranged from 0.2 to 1.0 μm in diameter. Thermal shock resistance was tested by heating the cermet to 520°C and quenching in hot water. Cermets that were gastight after 15 quench cycles were considered acceptable. Thermal shock resistance was improved by heating the as-pressed pellet to 1630°C and air cooling.

Download Full-text

Improvement Anti-Wear Additive and Thermal Shock Resistance of a New Generation High Speed Railway Vehicles by Disk Brake of Surface Treatment Material

The Proceedings of Ibaraki District Conference ◽

10.1299/jsmeibaraki.2003.295 ◽

2003 ◽

Vol 2003 (0) ◽

pp. 295-296

Author(s):

Jun SUGISAKI ◽

Hideto SUZUKI ◽

Masasi NAKAMURA ◽

Masaru AJIMA

Keyword(s):

Surface Treatment ◽

Thermal Shock ◽

Thermal Shock Resistance ◽

High Speed ◽

High Speed Railway ◽

Railway Vehicles ◽

Disk Brake ◽

Shock Resistance ◽

New Generation

Download Full-text

Carbide Particle-Reinforced Tungsten Composites in Extreme Hazard Environments

MAX Phases and Ultra-High Temperature Ceramics for Extreme Environments ◽

10.4018/978-1-4666-4066-5.ch017 ◽

2013 ◽

pp. 509-532

Author(s):

Guiming Song ◽

Yujin Wang ◽

Yu Zhou

Keyword(s):

Finite Element Method ◽

Thermal Shock ◽

Thermal Shock Resistance ◽

Early Stage ◽

Peripheral Zone ◽

Damage Mode ◽

Ablation Resistance ◽

Tic Particle ◽

Shock Resistance ◽

Disk Sample

The ablation as well as the associated thermal shock resistance of tungsten composites reinforced by TiC and ZrC particles is investigated with an oxyacetylene equipment. 30TiC/W (30TiC stands for 30 vol. % TiC particle content in tungsten, the same below) and 40TiC/W fail to withstand the thermal shock of 2000ºC/s during heating. In contrast, 30ZrC/W and 40ZrC/W withstand the thermal shock. Additionally, ZrC/W composites exhibit better ablation resistance than TiC/W composites. The thermal stress fields of the composite at both macro-/micro-scales induced by thermal shock at the early stage of the ablation are analyzed using finite element method. The calculated results of the damage mode of the composites show that crack initiates at the disk sample peripheral zone and then propagates to the sample center, which is consistent with the experimental observation.

Download Full-text