Medical Design Briefs - January 2022 - 16

Implantable Metals
ers. Also, it has a broad appeal to surface
treat many metallic materials used in medical
applications, such as titanium alloys, as
well as ferritic and austenitic stainless steel.
In addition, commercial heat-treat shops
have a wide variety of processing equipment
to choose from as well as a variety of
vendors. High-volume part producers can
select from multiple system configurations
that offer flexibility, efficiency, repeatability,
and throughput optimization. As a
result, manufacturers of medical device
products in Europe, North America, and
Asia are leveraging these systems to run a
cleaner, more efficient operation.
Pulse Plasma Nitriding Advantages
Commonly used alloys for medical
applications include a wide variety of
stainless steels, Commercially Pure (CP)
titanium, β-type titanium alloys, titanium-niobium
alloys, and specialty alloys,
all of which can have mechanical and
electrochemical properties enhanced by
carburizing (carburizing of titanium is
not usual) and nitriding.
Precision-controlled plasma nitriding continues to offer benefits such as the ability to bond dissimilar
metals. (Credit: PVA TePla)
This article looks at why precisioncontrolled
plasma nitriding continues to
offer benefits that leading manufacturers
depend on, and why the consumer-user
relies on unique materials processes for
reliable product quality.
Surface treatments are used in the
medical and dental industries for materials
such as stainless steel, titanium alloys,
cobalt-chrome alloys, and other specialty
alloys. Traditionally, these treatments
have included either carburizing, saltbath
nitrocarburizing, or gas nitriding.
Each process has advantages and disadvantages.
However, if one is seeking the
most precise control of the diffusion
16
Cov
layer formation to enhance material
properties, advanced pulse plasma
nitriding may offer the right solution.
Although pulse plasma nitriding has
been utilized for decades, superior controls
for the DC pulsing signal, along with
improved chamber design and construction,
allow for precise temperature control
and uniform distribution of the heat
zone throughout the hot-wall chamber.
The result is extremely consistent and uniform
nitriding batch-to-batch, with less
gas consumption per process when compared
to traditional nitriding methods.
The benefits of pulse plasma nitriding
include precise control of the diffusion laywww.medicaldesignbriefs.com
ToC
Due
to the high temperatures and
hold-time-at-temperature associated with
carburizing, which can lead to part distortion,
carburizing is not the preferred
method to treat materials used in medical
applications and is mainly used in
the aerospace and automotive industries.
However, a corrosion-resistant, martensitic
stainless steel alloy, known as BÖHLER
N360 has been successfully vacuum
carburized to a depth of 0.0015 in. as
indicated in the 2005 ASM International
document " Vacuum Carburizing of
Aerospace and Automotive Materials. " It
has been used in medical fastener applications
and for implantable devices.
An alternative to carburizing is nitriding,
a lower-temperature, time-dependent,
thermo-chemical process, used to
diffuse nitrogen into the surface of
metal. One method is salt bath nitriding.
In this process, liquid immersion is
required and is typically conducted at
550° to 570 °C. The salt bath process uses
the principle in which anhydrous ammonia
is dissolved in cyanide - forming
cyanate - a nitrogen-rich salt, often producing
a solution greater than 50 percent
in concentration. Salt bath nitriding,
which may have a duration of 24
hours, imparts unique improvements in
surface roughness, hardness and wear
resistance with the addition of a post
process of either air quenching or water
quenching. CP Grade 2 titanium is the
most formable and corrosion resistant
Medical Design Briefs, January 2022
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Medical Design Briefs - January 2022

Table of Contents for the Digital Edition of Medical Design Briefs - January 2022

Medical Design Briefs - January 2022 - Intro
Medical Design Briefs - January 2022 - Sponsor
Medical Design Briefs - January 2022 - Cov1a
Medical Design Briefs - January 2022 - Cov1b
Medical Design Briefs - January 2022 - Cov1
Medical Design Briefs - January 2022 - Cov2
Medical Design Briefs - January 2022 - 1
Medical Design Briefs - January 2022 - 2
Medical Design Briefs - January 2022 - 3
Medical Design Briefs - January 2022 - 4
Medical Design Briefs - January 2022 - 5
Medical Design Briefs - January 2022 - 6
Medical Design Briefs - January 2022 - 7
Medical Design Briefs - January 2022 - 8
Medical Design Briefs - January 2022 - 9
Medical Design Briefs - January 2022 - 10
Medical Design Briefs - January 2022 - 11
Medical Design Briefs - January 2022 - 12
Medical Design Briefs - January 2022 - 13
Medical Design Briefs - January 2022 - 14
Medical Design Briefs - January 2022 - 15
Medical Design Briefs - January 2022 - 16
Medical Design Briefs - January 2022 - 17
Medical Design Briefs - January 2022 - 18
Medical Design Briefs - January 2022 - 19
Medical Design Briefs - January 2022 - 20
Medical Design Briefs - January 2022 - 21
Medical Design Briefs - January 2022 - 22
Medical Design Briefs - January 2022 - 23
Medical Design Briefs - January 2022 - 24
Medical Design Briefs - January 2022 - 25
Medical Design Briefs - January 2022 - 26
Medical Design Briefs - January 2022 - 27
Medical Design Briefs - January 2022 - 28
Medical Design Briefs - January 2022 - 29
Medical Design Briefs - January 2022 - 30
Medical Design Briefs - January 2022 - 31
Medical Design Briefs - January 2022 - 32
Medical Design Briefs - January 2022 - 33
Medical Design Briefs - January 2022 - 34
Medical Design Briefs - January 2022 - 35
Medical Design Briefs - January 2022 - 36
Medical Design Briefs - January 2022 - 37
Medical Design Briefs - January 2022 - 38
Medical Design Briefs - January 2022 - 39
Medical Design Briefs - January 2022 - 40
Medical Design Briefs - January 2022 - Cov3
Medical Design Briefs - January 2022 - Cov4
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