Glass tougher than stainless steel:
Scientists have come up with a new type of glass from opaque titanium and zirconium, which is harder, tougher and weighs less than stainless steel. The glass has been developed by scientists at the Lawrence Berkeley National Laboratory, California, US. The experts who developed and tested the opaque glass hope it could one day replace steel and aluminum in a variety of products, from golf clubs to airplanes. The problem with most (types of) glass is that they have very bad fatigue resistance, meaning they break easily. What scientists have done is introduce a second phase that is able to improve the fatigue resistance. Now, it is as good as other high strength alloys like steel. To create the tough, metallic glass, the scientists first heat an alloy of half titanium and half zirconium to 8000 C until melt. The liquid metal is allowed to cool slowly for a minute or two, and then cooled very rapidly after that. By cooling slowly and then quickly, the scientists allowed tiny Christmas tree like crystalline structures to grow through the metal. Rapidly cooling the rest of the metal maintains the glassy atomic structure. The crystalline structures stop any cracks that from moving more than two to five microns in length. The glass gives the material its strength, while the Christmas tree structures give it toughness. In subsequent stress tests, the 1 to 10 centimeter pieces of glass were dramatically tougher than any previous metallic glass, a full order of magnitude more resistant to breaking and stronger than steel. Since the alloy is titanium and zirconium instead of steel, it weights significantly less than steel. It also melts at much lower temperatures than steel, making it easier and faster to produce. It also melts at much lower temperatures than steel, making it easier and faster to produce. They could make an airplane out of metallic glass. If this is possible, one day there would be a sea of change in aviation sector and the maintenance of airplanes would take a new shape in comparison to conventional maintenance.
Injection molded glass fiber reinforced plastics:
A new slant on the lightweight commuter bicycle has been developed by a UK Company using injection molded, glass fiber reinforced plastic parts. Although the design of the bicycle is based on a frame manufactured from magnesium, a specially formulated nylon filled with long glass fibers is used for crucial mechanical parts like the rear suspension unit. The expertise to injection mold this light weight yet strong material is 60% glass was provided by UK based Protomold. For the Shropshire Company it was a challenging project. It was not that the molding process was unusual, it was the materials they were using. The company’s senior engineers had never previously worked with a metal incorporating such high glass content. For this reason, the engineering team was uncertain how well the material would flow and pervade the cavity within the injection molding tool. With the Go Cycle parts they were really pushing the boundaries of what is possible with plastic, and therefore, the materials specified were, in the main, exotic thermoplastics. A very dominant material in the range is 60% long fiber glass filled nylon, which is pretty extreme in terms of the glass content, coupled with the fact that it’s long fiber. During the molding process, those fibers have a tendency to align with flow direction. The way the fibers are aligned affects the mechanical properties of the end part. Working closely with Karbon Kinetics, the bike’s UK Designer, Protomold scrutinized CAD geometry of all the components that required molding. The information was entered into Protomold’s in house flow analysis software, Protoflow, so that visual prognosis of the injection molding process could be established. The company’s engineering team then tested different locations points for where the plastic enters the cavity (known as gate) and analyzed the various pressure and temperature conditions required to achieve successful component molding. At the end of the project Protomold had developed a total of 47 individual injection molding tools, which were used to manufacture the required parts. On top of achieving mechanical properties, the engineers also had cosmetic requirements to achieve. Alongside GoCycle’s durability ethos, it was also intended to be as fashionable and lustrous. With this in mind, the majority of parts feature a shiny black specification, meaning Protomold engineers had to determine the precise velocity at which to inject the material into the cavity to ensure consistency of color.