Investigation of the Effects of Roller Spreading Parameters on Powder Bed Quality in Selective Laser Sintering.

Powder spreading is one of crucial steps in selective laser sintering (SLS), which controls the quality of the powder bed and affects the quality of the printed parts. It is not advisable to use empirical methods or trial-and-error methods that consume lots of manpower and material resources to match the powder property parameters and powder laying process parameters. In this paper, powder spreading in realistic SLS settings was simulated using a discrete element method (DEM) to investigate the effects of the powder's physical properties and operating conditions on the bed quality, characterized by the density characteristics, density uniformity, and flatness of the powder layer.

The chemisorption of tetracene on Si(100)-2x1 surface.

The adsorption of tetracene on Si(100)-2x1 substrate has been studied by ultraviolet photoemission spectroscopy (UPS). Six features deriving from the organic material are located at 1.22, 2.

Interfacial electronic states of tetracene deposited on Si(111).

The interfacial electronic states of tetracene on Si(111) 7x7 substrate were studied by using ultraviolet photoelectron spectroscopy (UPS). After deposition of tetracene on the Si(111) 7x7 surface, the features originating from the tetracene molecule appear at 1.55, 3.