Effects of Preparation Processes on the Properties of Fluoride Hydrophobic Films

The influences of various process conditions on the optical and hydrophobic properties of hydrophobic films were studied.Hydrophobic films with various properties were prepared by electron beam thermal evaporation by controlling the process parameters (deposition temperature,pressure and deposition rate).The refractive index,extinction coefficient and hydrophobic angle of the film under different conditions were analyzed.The transmittance of the antireflective film with the film structure of G/2HL/A was measured and analyzed.The results show that for 550 nm wavelength,when the deposition temperature increases from room temperature to 180℃,the refractive index varies from 1.4595 to 1.5559,the extinction coefficient varies from 3.46×10^-3 to 6.8×10^-3,and the variation range of hydrophobic angle from 85.1°to 119.3°.The results show that with the increase in deposition temperature,the refractive index of the film increases,the extinction coefficient increases slightly,but the effect is small,and the hydrophobicity of the film increases first and then decreases.When the pressure increases from 3×10^-2Pa to 1×10^-2Pa,the refractive index varies from 1.4136 to 1.5476,the extinction coefficient varies from 3.94×10^-3 to 5.3×10^-3,and the variation range of hydrophobic angle from 97.3°to 119.3°.The results show that with the increase in working vacuum,the refractive index of the film increases,and the hydrophobicity decreases.As the deposition rate increases from 0.33 nm/s to 0.91 nm/s,the refractive index varies from 1.4946 to 1.5838,the extinction coefficient increases from 4.14×10^-3to 7.87×10^-3,and the variation range of hydrophobic angle from 106.6°to 119.3°.The results show that with the increase in the deposition rate,the refractive index of the film is also increased,the extinction coefficient of the film is slightly improved,and its value is not much different.When the deposition temperature is 160℃,the pressure is 1×10^-2Pa and the deposition rate is 0.51 nm/s,the hydrophobic film has the best hydrophobic performance,and the hydrophobic angle is up to 119.2°.Under the optimum process parameters,a hydrophobic film with a thickness of about 10 nm is plated on the surface of the antireflection film.From 400 nm to 800 nm,the average transmittance of single-sided coating changes from 95.28%to 95.31%,the variation is only 0.03%,and the hydrophobic angle can reach 119.2°.The results show that the hydrophobic film has good optical properties and hydrophobic ability.