Theoretical study of reactive melt infiltration to fabricate Co-Si/C composites

Abstract

Cobalt-silicon based carbon composites (Co–Si/C) have established a noteworthy consideration in recent years as a replacement for conventional materials in the automotive and aerospace industries. To achieve the composite, a reactive melt infiltration process (RMI) is used, in which a melt impregnates a porous preform by capillary force. This method promises a high-volume fraction of reinforcement and can be steered in such a way to get the good “near-net” shaped components. A mathematical model is developed using reaction-formed Co–Si alloy/C composite as a prototype system for this process. The wetting behavior and contact angle are discussed; surface tension and viscosity are calculated by Wang’s and Egry’s equations, respectively. Pore radii of 5 μm and 10 μm are set as a reference on highly oriented pyrolytic graphite. The graphs are plotted using the model, to study some aspects of the infiltration dynamics. This highlights the possible connections among the various processes. In this attempt, the Co–Si (62.5 at.% silicon) alloy’s maximum infiltration at 5 μm and 10 μm radii are found as 0.05668 m at 125 s and 0.22674 m at 250 s, respectively.

Oxymetazoline hydrochloride ophthalmic solution, 0.1%, boosts the effects of botulinum toxin on blepharospasm: a case series

“…The precise biochemical mechanism for the effect of oxymetazoline hydrochloride ophthalmic solution (0.1%) on blepharospasm is still being researched, but some preliminary conclusions can be drawn. Because oxymetazoline hydrochloride ophthalmic solution (0.1%) stimulates contractions in Müller's muscle, and Müller's muscle is responsible for maintaining upper eyelid elevation, reductions in blepharospasm may have been due to the strengthening of Müller's muscle according to findings from an earlier study [5]. The results from another earlier study also suggested that the upper eyelids would remain elevated, preventing involuntary closure of the eyelids resulting from these spasms [7].…”

“…Abnormally low-lying upper eyelids is a condition known as blepharoptosis [5]. Blepharoptosis can be classified as acquired, neurogenic, myogenic, mechanical, aponeurotic, or traumatic [5].…”

“…Abnormally low-lying upper eyelids is a condition known as blepharoptosis [5]. Blepharoptosis can be classified as acquired, neurogenic, myogenic, mechanical, aponeurotic, or traumatic [5]. The severity of blepharoptosis can range from mild to severe, with mild blepharoptosis having less impact on the visual field than severe blepharoptosis [5].…”

“…This ophthalmic solution (0.1%) works by increasing the activity of Müller's muscle α-adrenergic receptors, leading to stronger contractions in Müller's muscle [7], the normal function of which is to keep the upper eyelids elevated. Blepharoptosis may arise if Müller's muscle is damaged or weakened or if levator dehiscence is present [5].…”