California Glass Expert Discusses Nickel Sulfide in Tempered Glass

In glass failure analysis one uses evidence such as the the attached photograph to demonstrate that a nickel sulfide particle can initiate tempered glass failure. The NiS particle is at the center of expanding Wallner lines. The Wallner lines are used by the glass failure analysis expert to track the direction of the crack growth. In this case the Wallner lines are spreading from a single point; thus, this is the failure origin and the NiS particle is the cause of the tempered glass failure. The California glass expert has seen numerous examples of this type of glass failure.

Tempered Glass Expert Shows Multple Views of Nickel Sulfide Particle

The result of a failure analysis, a glass expert presents several views of a 180µ diameter origin (nickel sulfide particle) of a failed tempered glass door. The upper left photomicrograph is taken with a low power optical microscope and it includes the NiS particle and the initial Wallner lines. Upper right and lower left are taken with a high power optical microscope. with and without Nomarski. Finally lower right is an Scanning electron microscope photomicrograph of the same particle. The inportance here is that the distinct shape and surface of a NiS particle makes it identifiable with an optical microscope.

Glass Failure Analysis of Laminated and Tempered GLass

Glass failure analysis was performed by a failure analysis expert on a large laminated window of which one layer was tempered glass. The tempered half of the lamination failed. The other half of the window held the system together, and this allowed a failure analysis to be performed. The upper left photo is an over view of the window failure. The arrow indicates the general location of the failure origin of the tempered glass layer. The upper right photo is a closeup of the origin. The arrow indicates the location of a nickel sulfide particle (NiS) that caused the failure. It was reported that the tempered glass had been heat soaked. In this case the heat soak test (HST) did not eliminate on this window before it was sold.

Failure Analysis Expert Performs Glass Failure Analysis

Glass expert performs a failure analysis on a failed tempered glass door. The spontaneous glass failure was analyzed to determine the cause of failure. This was one of several doors that failed spontaneously on a new high rise. Fortunately the door did not fall apart; thus, the failure origin could be preserved. The upper left photo shows the failure origin (arrow). The origin was taken apart, and at the center was a spherical 180 micron diameter nickel sulfide particle, NiS particle. During the glass failure analysis, a scanning electron microscope, SEM, image of the particle is shown in the upper right. Elemental analysis of the particle showed it to consist of nickel and sulfur. The SEM image also shows initial Wallner lines that are spiral in shape and are leaving the particle. This identifies the NiS particle as the cause of the failure

Glass Failure Expert Looks at Tempered Glass Failure

Glass expert analyzed a broken tempered glass door. He was able to preserve the origin and perform a failure analysis. The spontaneous glass failure started in the center of the window and was caused by a nickel sulfide particle (NiS particle). This failure mechanism is well known and has been documented by others. In this case, the glass expert spent some time documenting the initial crack growth. The upper left photomicrograph shows two sets of Wallner lines spreading away from the general location of the 100 micron diameter spherical nickel sulfide particle. The photomicrograph on the upper right shows a circular crack arrest line surrounding the NiS particle. This circular artifact identifies the NiS particle (a manufacturing defect) as the cause of the failure. In addition, it also indicates that the crack stopped at least once before the glass went to failure. At first the crack started as a round crack due to the stresses from the nickel sulfide particle. Later the residual stresses in the glass took control. The circular crack opened up and turned into the classic sets of Wallner lines found in root cause failure analysis of tempered glass.