Investigation of Metal-Ceramic Bond Strength in Co-Cr Alloys Produced by Selective Laser Melting at Different Laser Powers.

Purpose: The purpose of this in vitro study was to evaluate the effects of laser power on the relative density, surface roughness, and metal-ceramic bond strength of Co-Cr alloys produced by selective laser melting (SLM), following a single laser track analysis to determine suitable processing parameter window.

Material and methods: Single track laser melting was performed at various laser powers and scanning speeds using SLM. Subsequently, three different laser powers (240 W, 300 W, 360 W) were used to produce 12×12×10 mm cube specimens and 25×3×0.5 mm metal strips. The density of the cube specimens (n=5) was determined using the Archimedes method. Microstructural investigations were conducted after metallographic preparation using scanning electron microscope (SEM). Surface roughness of the sandblasted metal strip specimens (n=9) was measured. Ceramic was applied to metal specimens (n=10) in each group, and the strength of the metal-ceramic bond was evaluated through a three-point bend test.

Results: SEM analysis showed improved laser track clarity, thickness, and continuity with increasing laser power from 240 W to 360 W. Relative density exceeded 99% for all specimens, with no significant group differences (P=.90). Higher laser power caused keyhole formation and increased surface roughness, peaking at 11.89 ± 3.86 Sa for the P360 group (P<0.01). Specimens produced with the highest laser power demonstrated stronger and more consistent metal-ceramic bond strengths, with significant differences observed between the highest (360 W) and the lowest (240 W) power group (P<.05).

Conclusion: While increased laser power enhanced surface roughness and strength of the metal-ceramic bond, it did not lead to substantial changes in the relative density of the specimens.