Effects of Laser Radiation on the Wetting and Diffusion Characteristics of Kovar Alloy on Borosilicate Glass

Abstract

The purpose of this study was to investigate the advantages of laser surface melting for improving wetting over the traditional approach. For comparison, kovar alloy was preoxidized in atmosphere at 700 °C for 10 min, and then wetted with borosilicate glass powder at 1100 °C with different holding time in atmosphere. The proposed approach used a Nd:YAG laser to melt the surface of the kovar alloy sample in atmosphere, then wetted with borosilicate glass powder at 1100 °C with the same holding time. The laser melted surface shows a decrease in contact angle (CA) from 47.5 deg to 38 deg after 100 min. X-ray photoelectron spectroscopy (XPS) analysis shows that the surface and adjacent depth have higher concentration of FeO for laser treated kovar (Kovar(L)) than that on traditional thermal treated kovar (kovar(P)). This is attributed to the following improved wetting and diffusion process. The adhesive oxide layer formed on kovar (L) may enhance the oxygen diffusion into the substrate and iron diffusion outward to form an outside layer. This is an another way to enhance the wetting and diffusion process when compared to the delaminated oxide scales formed on kovar (P) surface. The diffusion mechanisms were discussed for both approaches. Scanning electron microscope (SEM) revealed that an iron oxide interlayer in the joint existed under both conditions. Fayalite nucleated on the iron oxide layer alloy and grew into the glass. In both cases, neither Co nor Ni were involved in the chemical bonding during wetting process. The work has shown that laser surface melting can be used to alter the wetting and diffusion characteristics of kovar alloy onto borosilicate glass.

Experimental Study on the Laser Transmission Joining of Polystyrene and Titanium

“…The essence of the laser surface treatment includes scanning the titanium metal surface by the laser in the air atmosphere, oxidizing by heating, and forming an oxide layer of a certain thickness on the metal surface [ 20 ]. Figure 1 shows the samples of the titanium surface treated by the laser power for surface treatment of 4 W, 5 W, and 6 W. The scanning speed was 2 mm/s, the number of scans was six, and the spot diameter was 2 mm.…”

“…Plasma treatment is an effective method for the surface modification of polymers [ 20 ]. In this study, plasma treatment apparatus (HD-1B, Changzhou Zhongke Changtsi Plasma Processing Apparatus Plasma Technology Co., Ltd., Changzhou, China) was used.…”

Microscopic Analysis of the Wetting Morphology and Interfacial Bonding Mechanism of Preoxidised Kovar Alloys with Borosilicate Glass

“…Therefore, in this study, the optimum oxidation temperature and holding time of Kovar alloys were investigated using a preoxidation method with a borosilicate glass matching sealer to examine the different formation patterns of oxide layers generated on the alloy surface. The bonding between different preoxidised Kovar alloys and high-borosilicate glass was then investigated, and further comprehensive microscopic analysis of the wetting and spreading morphology of Kovar and preoxidised high-borosilicate glass and the interfacial bonding mechanism was carried out based on the research by Chen [ 23 ].…”

Improvement of Laser Transmission Welding of Glass with Titanium Alloy by Laser Surface Treatment

“…Chern et al improved the wettability and tightness of 7056 glass on a Kovar surface by pre-oxidizing the surface of Kovar alloy using a furnace thermal treatment [ 18 ]. Zhang et al improved the wettability and diffusivity of borosilicate glass on the surface of Kovar alloy by laser melting oxidation of metal surfaces [ 19 ]. Li et al improved the joint strength of PS and titanium using the two pretreatment methods (laser oxidization treatment and oxygen plasma surface treatment) [ 20 ].…”