Biomedical Engineering Reference
In-Depth Information
development have taken place at various research facilities thereafter. These
include the Russian Academy of Science, Sandia National Laboratories, and
ASB Industries, among others (Papyrin, 2001). To compare experimental data
to analytical models, existing analytical models were explored to find a basic
first order model to allow for comparison and prediction of particle velocities.
A formula for predicting projectile velocity as a function of position is found,
and is used to compare data collected from a vacuum cannon (Ayars and
Buchholtz, 2004). Aside from thermal spray and cold spray processes,
alternative methods of developing a pneumatic device were sought. This
included the investigation of fast-acting valves for this application (Morgan
and Stalker, 1983) and the use of burst discs as a firing method. Burst discs,
also referred to as diaphragm valves, were investigated to find how the
opening time compares with traditional solenoid valves (Baksht and Fedyunin,
1988). Additional alternative methods sought were pneumatic capillary guns,
which fire single microparticles (Rinberg et al., 2005), and gas guns used for
fueling nuclear fusion devices, which typically fire deuterium pellets several
millimeters in diameter at supersonic speeds (Frattolio et al., 1999; Viniar and
Sudo, 1997).
2.2. Findings on the Problem and the Purpose
Relevant findings of previous research are presented. In the early
twentieth century, Dr. Max Ulrich Schoop discovered it was possible to bond
particles of one metal to another by depositing the particles in molten form
(Hermanek, 2002). This method became known as molten metal flame spray, a
type of thermal spray. Subsequent improvements were made to this method,
and other thermal spray methods were developed, and can be categorized into
two categories: flame spraying and electrical spraying (Hermanek, 2002).
Flame spraying processes include powder, wire, ceramic rod, detonation, and
high velocity oxy-fuel. Electrical spraying processes include non-transferred
arc plasma, electric arc, and RF plasma (Hermanek, 2002). All of these
thermal processes, however, include addition of heat such that the deposited
particles are in molten form.
It was not until the 1980s that the cold spray process was developed.
Unlike thermal spray, in the cold spray process particles are accelerated and
impacted into a substrate material in the solid state. This process was
developed by Anatolli Papyrin in Russia (Papyrin, 2001). Studies have
attempted to determine combinations of particle speed, size, and material that
