Search results
Results from the WOW.Com Content Network
Epitaxial thin films may experience stresses from misfit strains between the coherent lattices of the film and substrate, and from the restructuring of the surface triple junction. [27] Thermal stress is common in thin films grown at elevated temperatures due to differences in thermal expansion coefficients with the substrate. [28]
The challenge of characterizing thin films involves extracting t, n(λ) and k(λ) of the film from the measurement of R(λ) and/or T(λ). This can be achieved by combining the Forouhi–Bloomer dispersion equations for n ( λ ) and k ( λ ) with the Fresnel equations for the reflection and transmission of light at an interface [ 21 ] to obtain ...
The basic form of a 2-dimensional thin film equation is [3] [4] [5] = where the fluid flux is = [(+ ^) + ^] +, and μ is the viscosity (or dynamic viscosity) of the liquid, h(x,y,t) is film thickness, γ is the interfacial tension between the liquid and the gas phase above it, is the liquid density and the surface shear.
Depending on the substrate material and surface finish, TiN has a coefficient of friction ranging from 0.4 to 0.9 against another TiN surface (non-lubricated). The typical TiN formation has a crystal structure of NaCl type with a roughly 1:1 stoichiometry ; TiN x compounds with x ranging from 0.6 to 1.2 are, however, thermodynamically stable.
The heat transfer coefficient is often calculated from the Nusselt number (a dimensionless number). There are also online calculators available specifically for Heat-transfer fluid applications. Experimental assessment of the heat transfer coefficient poses some challenges especially when small fluxes are to be measured (e.g. < 0.2 W/cm 2). [1] [2]
As implied by the name, diamond-like carbon (DLC), the value of such coatings accrues from their ability to provide some of the properties of diamond to surfaces of almost any material. The primary desirable qualities are hardness, wear resistance, and slickness (DLC film friction coefficient against polished steel ranges from 0.05 to 0.20 [10]).
The thickness of the film thus exceeds the combined roughness of the surfaces. The coefficient of friction is lower than with boundary-layer lubrication. Hydrodynamic lubrication prevents wear in moving parts, and metal to metal contact is prevented. Hydrodynamic lubrication requires thin, converging fluid films.
Low coefficient of friction (AF-4, HT, SF) Since the coating process takes place at ambient temperature in a mild vacuum, it can be applied even to temperature-sensitive objects such as dry biological specimens. The low temperature also results in low intrinsic stress in the thin film. Moreover, the only gas in the deposition chamber is the ...