Effect of Film Thickness on Fatigue Strength of TiAl Alloy Coated with TiAlN Film at Elevated Temperature

2005 ◽  
Vol 297-300 ◽  
pp. 1446-1451 ◽  
Author(s):  
Takeshi Kasuya ◽  
Hideto Suzuki
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
Film Thickness ◽  
Thick Film ◽  
Physical Vapor Deposition ◽  
Tial Alloy ◽  
Testing Machine ◽  
Intermetallic Alloy ◽  
Fracture Control ◽  
The Difference

The fatigue strength of TiAl intermetallic alloy coated with TiAlN film was studied in vacuum at 1073K using a SEM-servo testing machine. In addition, three kinds of TiAlN films were given by physical vapor deposition (1, 3, and 10μ m). The fatigue strength of 3μ m was highest. Also, the fatigue strength of 1μ m was lowest. From this result, existence of optimum film thickness was suggested because the difference of fatigue strength arose in each film thickness. The justification for existence of optimum film thickness is competition of 45-degree crack and 90-degree crack. The 45-degree crack is phenomenon seen in the thin film (1μ m), and is caused by plastic deformation of TiAl substrate. The 45-degree crack is the factor of the fatigue strength fall by the side of thin film. In contrast, the 90-degree crack is phenomenon in the thick film (10μ m), and is caused as result of reaction against load to film. The 90-degree crack is the factor of the fatigue strength fall by the side of thick film. In conclusion, the optimum film thickness can perform meso fracture control, and improves fatigue strength.

Fatigue Properties of Nitride Cr-Mo Steel with CrN Thin Film Deposited by Aip Method

2003 ◽  
Vol 17 (08n09) ◽  
pp. 1554-1559 ◽  
Author(s):  
Daisuke Yonekura ◽  
Atsushi Tsukuda ◽  
Ri Ichi Murakami ◽  
Koji Hanaguri
Keyword(s):  
Thin Film ◽  
Residual Stress ◽  
Fatigue Strength ◽  
Film Thickness ◽  
Compressive Residual Stress ◽  
Optical Microscope ◽  
Fatigue Tests ◽  
Fatigue Properties ◽  
Bending Fatigue ◽  
Three Point Bending

In this study, we selected the nitride Cr-Mo Steel SCM435 as the substrate. Attention was focussed on the effect of film thickness. The Arc Ion Plating was performed using Cr cathode and N2 gas. The specimens were prepared for the film thickness 6, 12 and 18μm The three point bending fatigue tests were performed at room temperature in a laboratory environment. After the fatigue test, crack initiation sites were examined by using an optical microscope and a scanning electron microscope. The results obtained were as follows: (1) A high compressive residual stress generated in the film, and the compressive residual stress of 12μm film thickness was the greatest. (2) The fatigue strength of coated specimens for thin film was slightly lower than for substrate. (3) The film thickness hardly affected the fatigue strength of coated specimens.

scholarly journals Compressible Stokes Flow in Thin Films

2003 ◽  
Vol 125 (3) ◽  
pp. 543-551 ◽  
Author(s):  
D. E. A. van Odyck ◽  
C. H. Venner
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Film Thickness ◽  
Stokes Flow ◽  
Reynolds Equation ◽  
Stokes Equations ◽  
Contact Length ◽  
Solution Algorithm ◽  
Compressible Medium ◽  
The Difference

A multigrid numerical solution algorithm has been developed for the laminar (Stokes) flow of a compressible medium in a thin film. The solver has been applied to two model problems each representative of lubrication problems in a specific way. For both problems the solutions of the Stokes equations are compared with the solutions of the Reynolds equation. The configurations of both model problems were chosen such that based on the ratio film thickness to contact length (H/L) the difference between the Reynolds and the Stokes solutions will be very small, so the geometry of the gap itself does not lead to a significant cross film dependence of the pressure. It is shown that in this situation the compressibility can still lead to a cross-film pressure dependence which is predicted by the Stokes solution and not by the Reynolds solution. The results demonstrate that limitations exist to the validity of the Reynolds equation related to the compressibility of the medium.

scholarly journals Skin protection against UV radiation using thin films of cerium oxide

2019 ◽  
Vol 54 (1) ◽  
pp. 67-70 ◽  
Author(s):  
E. Ortiz ◽  
L. Martínez-Gómez ◽  
J.F. Valdés-Galicia ◽  
R. García ◽  
M. Anzorena ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Radiation Dose ◽  
Film Thickness ◽  
Titanium Oxide ◽  
Cerium Oxide ◽  
Thin Film Thickness ◽  
Skin Sample ◽  
Alternative Material ◽  
The Difference

In this work, we evaluated the efficiency of cerium oxide as sunscreen using titanium oxide as standard comparison material. Geant4 software was used to perform numerical simulation, we calculated the radiation dose that ultraviolet radiation deposits in a skin sample as a function of thin film thickness of the sunscreens. We found that in the interval between 5 and 15 nm of the thin film thickness and for wavelengths between 160 and 400 nm, cerium oxide has the potential to reduce the radiation dose more than 10% with respect to the same thickness band of titanium oxide. Using thin films of cerium oxide and titanium oxide with same thicknesses and greater than 45 nm, the difference in the attenuation of the radiation dose for both materials is less than 1%. The results lead us to propose cerium oxide as an alternative material to titanium oxide for the manufacture of sunscreens.

Rheological Characteristics for Thin Film Elastohydrodynamic Lubrication with Non-Newtonian Lubricants

2007 ◽  
Vol 23 (4) ◽  
pp. 359-366
Author(s):  
H.-M. Chu ◽  
Y.-P. Chang ◽  
W.-L. Li
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Velocity Distribution ◽  
Adsorption Layer ◽  
Elastohydrodynamic Lubrication ◽  
Middle Layer ◽  
Flow Index ◽  
Thin Film Lubrication ◽  
The Difference ◽  
Index Ratio

AbstractThe modified Reynolds equation for power law fluid is derived from the viscous adsorption theory for thin film elastohydrodynamic lubrication (TFEHL). The differences between classical non-Newtonian EHL and non-Newtonian TFEHL are discussed. Results show that the proposed model can reasonably calculate the pressure distribution, the film thickness, the velocity distribution and the average viscosity under thin film lubrication. The thickness (δ), the viscosity (m1), and the flow index (n1) of the adsorption layer influence significantly the lubrication characteristics of the contact conjunction. Furthermore, the film thickness increases with the increase of n1 and the film thickness affected by m1 is greater than that affected by n1, but the effect of n1 produces a very small difference in the pressure distributions. In addition, the greater n1, the smaller the change of velocity distribution in the adsorption layer, and the greater the change of velocity distribution in the middle layer. The larger δ and n1, the larger the deviation on log (film thickness) vs. log (speed) produced in the very thin film regime. In the region of the flow index ratio between 1.0 and 1.3, the difference in film thickness is significant. When the flow index of the adsorption layer is 1.6 times greater than the flow index of the middle layer, the adsorption layer is generally looked upon as a “solid-like”.

Fatigue Test of Al-3%Ti Using Axial Loading Testing Machine for RF MEMS Switch

2006 ◽  
Vol 110 ◽  
pp. 3-8 ◽  
Author(s):  
Jun Hyub Park ◽  
Chang Seung Lee ◽  
Yun Jae Kim
Keyword(s):  
Thin Film ◽  
Fatigue Strength ◽  
High Cycle Fatigue ◽  
Rf Mems ◽  
Testing Machine ◽  
Axial Loading ◽  
Tensile Tests ◽  
Fatigue Properties ◽  
Cycle Fatigue ◽  
Mems Switch

This paper presents high cycle fatigue properties of a Al-3%Ti thin film, used in a RF (radio-frequency) MEMS switch for a mobile phone. The thickness and width of the thin film of specimen are 1.1μm and 480.0μm, respectively. Tensile tests of five specimens are performed, from which the ultimate strength is found to be 144MPa. High cycle fatigue tests of six specimens are also performed, from which the fatigue strength coefficient and the fatigue strength exponent are found to be 336MPa and –0.1514, respectively.

scholarly journals Simulation and Optimization of Film Thickness Uniformity in Physical Vapor Deposition

Coatings ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 325 ◽  
Author(s):  
Ben Wang ◽  
Xiuhua Fu ◽  
Shigeng Song ◽  
Hin Chu ◽  
Desmond Gibson ◽  
...  
Keyword(s):  
Thin Film ◽  
Film Thickness ◽  
Vapor Deposition ◽  
Physical Vapor Deposition ◽  
Thickness Distribution ◽  
Large Area ◽  
Thickness Uniformity ◽  
Simulation And Optimization ◽  
Material Sources ◽  
Good Agreement

Optimization of thin film uniformity is an important aspect for large-area coatings, particularly for optical coatings where error tolerances can be of the order of nanometers. Physical vapor deposition is a widely used technique for producing thin films. Applications include anti-reflection coatings, photovoltaics etc. This paper reviews the methods and simulations used for improving thin film uniformity in physical vapor deposition (both evaporation and sputtering), covering characteristic aspects of emission from material sources, projection/mask effects on film thickness distribution, as well as geometric and rotational influences from apparatus configurations. Following the review, a new program for modelling and simulating thin film uniformity for physical vapor deposition was developed using MathCAD. Results from the program were then compared with both known theoretical analytical equations of thickness distribution and experimental data, and found to be in good agreement. A mask for optimizing thin film thickness distribution designed using the program was shown to improve thickness uniformity from ±4% to ±0.56%.

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