Na Fan, Liqiang Chai, Peng Wang and Jun Liang
This paper aims to study the tribocorrosion behavior of 304 stainless steel (SS) sliding against SiC and Si3N4 counterparts in artificial seawater.
Abstract
Purpose
This paper aims to study the tribocorrosion behavior of 304 stainless steel (SS) sliding against SiC and Si3N4 counterparts in artificial seawater.
Design/methodology/approach
The tribocorrosion behavior of 304SS sliding against SiC and Si3N4 balls in artificial seawater has been investigated. The tests were conducted using a ball-on-disk rig equipped with an electrochemical workstation. The friction coefficient, surface morphology, wear volume and current density were determined.
Findings
When 304SS sliding against SiC ball, a smooth surface with a silica layer was formed on the top, which led to the low friction coefficient, current density and small wear volume. For 304SS-Si3N4 tribo-pair, a lot of metal debris was scattered on contact surfaces leading to high friction coefficient, current density and big wear volume.
Research limitations/implications
This research suggests that the lubrication effect of silicon-based ceramics is related to counterpart specimen in artificial seawater.
Practical implications
The results may help us to choose the appropriate ceramic ball under seawater environment.
Originality/value
The main originality of the work is to reveal the tribocorrosion behavior of 304SS sliding against SiC and Si3N4 balls, which help us to realize that the Si3N4 ball as water-lubricated ceramics could not exhibit lubrication effect when coupled with 304SS in artificial seawater.
Details
Keywords
Abstract
Purpose
The purpose of this paper is to study the variation of the mechanical strength and failure modes of solder balls with reducing diameters under conditions of multiple reflows.
Design/methodology/approach
The solder balls with diameters from 250 to 760 µm were mounted on the copper-clad laminate by 1-5 reflows. The strength of the solder balls was tested by the single ball shear test and pull test, respectively. The failure modes of tested samples were identified by combing morphologies of fracture surfaces and force-displacement curves. The stresses were revealed and the failure explanations were assisted by the finite element analysis for the shear test of single solder ball.
Findings
The average strength of a smaller solder ball (e.g. 250 µm in diameter) is higher than that of a larger one (e.g. 760 µm in diameter). The strength of smaller solder balls is more highly variable with multiple reflows than larger diameters balls, where the strength increased mostly with the number of reflows. According to load-displacement curves or fracture surface morphologies, the failure modes of solder ball in the shear and pull tests can be categorized into three kinds.
Originality/value
The strength of solder balls will not deteriorate when the diameter of solder ball is decreased with a reflow, but a smaller solder ball has a higher failure risk after multiple reflows. The failure modes for shear and pull tests can be identified quickly by the combination of force-displacement curves and the morphologies of fracture surfaces.