Friday, April 25, 2008

Nano-Coating Replaces Cylinder Liners for Advanced Engines

Ford Research Centre Aachen (Germany) is developing a thermally sprayed nano-coating using a Plasma Transferred Wire Arc (PTWA) process that could replace the heavier cast iron liners that provide the necessary wear resistance of cylinder bores in aluminum block engines.
The thin, wear-resistant coating reduces weight and improves friction performance while delivering equal durability and reliability. Fuel consumption can be reduced by utilizing lightweight construction as well as by decreasing internal friction losses in the drive train.
Modern engine blocks are partly made of cast iron or aluminum material whereas for the later hypo-eutectic AlSi-alloys dominate. Due to the low hardness, surfaces made of these alloys cannot be used as a friction partner for the piston rings. Cast iron liners are often inserted into the engine block to provide a wear-resistant surface for the piston rings. This work describes how cast iron liners can be replaced by thin, nanocrystalline iron based coatings in order to decrease friction losses as well as reduce the engine weight.

Thursday, April 10, 2008

Diamond Like Carbon for Data and Beer Storage

Carbon-based materials play a major role in today's science and technology. Carbon is a very versatile element that can crystallize in the form of diamond and graphite. In recent years, there have been continuous and important advances in the science of carbon such as chemical vapor deposition of diamond1 and the discovery of fullerenes2, carbon nanotubes3 and 4, and single-layer graphene5. There have also been major developments in the field of disordered carbons. In general, an amorphous carbon can have any mixture of sp3, sp2, and even sp1 sites, with the possible presence of hydrogen and nitrogen. The compositions of nitrogen-free carbon films are conveniently shown on a ternary phase diagram ( Fig. 1). An amorphous carbon with a high fraction of diamond-like (sp3) bonds is known as diamond-like carbon (DLC). Unlike diamond, DLC can be deposited at room temperature, which is an important practical advantage. DLCs possess an unique set of properties, which has lead to a large number of applications such as, for example, magnetic hard disk coatings; wear-protective and antireflective coatings for tribological tools, engine parts, razor blades, and sunglasses; biomedical coatings (such as hip implants or stents); and microelectromechanical systems6
Ultrathin DLC films also enable ultrahigh-density data storage in magnetic and optical disks and ultralong shelf life for beer canned in plastic bottles. In the first case, up to 1 Tbit/in2 can be reached using sub-2 nm, atomically smooth films that act as a corrosion barrier to the recording medium. In the second case, hydrogenated amorphous carbons in the 100 nm thickness range provide a gas permeation barrier and enable standard polyethylene terephthalate (PET) bottles to efficiently store beer and carbonated soft drinks for tens of weeks.