Preparation and Performance of a Waterborne UV/Al Low Infrared Emissivity Coating

Shape and size design, preparation and test evaluation of color unit in visible light and infrared camouflage

This study presents a novel method for designing and preparing a visible light-infrared-compatible camouflage sample based on the shape, size of the visible band's color unit and the infrared band's material coatings. The coatings were prepared by using the cold spray method on 1 m × 1 m aluminum substrates with a color unit of the regular hexagonal sample (M1) and regular quadrilateral sample (M2). Then the color difference, the temperature difference and image salience value methods were used to analyze the effectiveness of camouflage samples through the real-scene tests. The results indicate that designed and prepared compatible camouflage samples are effective in their surrounding environment. Meanwhile, it can be concluded that M1 has high fusion with a background in visible and infrared bands compared to M2, M1 has 90.6% color similarity and only 0.8% temperature difference, the M2 has 85.4% color similarity and 1.6% temperature difference with the green background. These findings indicate that the cold spray method could compensate for conventional visible light camouflage design limitations. The combination of camouflage color unit design and visible/infrared material coating could be helpful in optical camouflage research. Furthermore, to improve the military equipment's survival time on the battlefield.

UV-curable self-matting waterborne polyurethane acrylate coating via self-wrinkled surface during curing in open-air

This study developed and evaluated a series of ultraviolet (UV) curable self-matting waterborne polyurethane acrylate (UV-WPUA) coatings based on the self-wrinkled surface during UV-curing in the open-air. This method is simple, efficient, eco-friendly, and it does not require complicated or expensive equipment. The FT-IR spectrum indicates that the peaks of C[double bond, length as m-dash]C in UV-WPUA have disappeared after UV irradiation. The gloss value of the UV-WPUA cured film can be affected by the wrinkles on the surface of the film and adjusted it by controlling the content of the photoinitiator in the liquid coating, since the content influences the dimensions of the wrinkles. As the height of the wrinkle increased, the gloss value of the UV-WPUA cured film decreased, and when the incident angles are 20° and 60°, the gloss values are less than 3 GU and 5 GU, respectively. Moreover, the cured film has a maximum water contact angle of 109°, which is affected by wrinkles and positively correlated with the surface roughness of the film. Furthermore, the cured film has excellent properties of thermal stability, tensile strength, pencil hardness, cross-cut adhesion and resistance to abrasion properties, making it well suited for the furniture, leather, and textile applications.

Modeling and Predicting the Machined Surface Roughness and Milling Power in Scot’s Pine Helical Milling Process

Helical milling with the advantages of stable machining process, a well-machined surface quality, etc., is an interest of researchers and producers. Machined surface roughness (arithmetic mean deviation (Ra) and maximum height of the assessed profile (Rz)) and milling power consumption as two main machining characteristic parameters were studied and chosen as response factors to evaluate the machinability of Scots pine helical milling. Input variables included helical angle of milling cutter, rotation speed of main shaft, and depth of milling. Response surface methodology was applied for the design of experiments, data processing and analysis, and optimization of the processing parameters. The results showed that Ra and Rz decreased with an increase in helical angle and rotation speed of main shaft, though increased with an increase in depth of milling. Milling power increased when the helical angle and depth of milling increased and showed a slight downward trend as the rotational speed increased. The quadratic models were applied to predict the values of Ra, Rz, and milling power due to the high values of R2 of 0.9895, 0.9905, and 0.9885, respectively. The plot of predicted and actual values also indicated that the created models had good predictability. The optimized combination of helical angle, rotation speed, and depth of milling are 64°, 7500 r/min, and 0.5 mm, respectively. The effects of input variables and the quantitative relation between input variables and response variables were revealed clearly. These achievements will be useful for guiding the selection of helical milling parameters to achieve the purposes of improving processed surface quality and saving the processing power consumption.