Titanium is the perfect metal to make replacement human body parts
Titanium is the perfect metal to make replacement human body parts
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Titanium material is expensive and can be problematic when it
comes to traditional processing technologies. For example, its high melting point (1,670℃, much higher than steel
alloys) is a challenge.
The relatively low-cost precision of 3D printing is therefore a game-changer for titanium. 3D printing is where an object
is built layer by layer and designers can create amazing shapes.
This allows the production of complex shapes such as replacement parts of a jaw
bone, heel, hip, dental implants, or cranioplasty plates in surgery. It can also be used to
make golf clubs and aircraft components.
The CSIRO is working with industry to develop new technologies in 3D printing using titanium. (It
even made a dragon out of titanium.)
Advances in 3D printing are opening up new avenues to further improve the function of customised bodypart
implants made of titanium.
Such implants can be designed to be porous, making them lighter but allowing blood, nutrients and nerves to pass through
and can even promote bone in-growth.
Safe in the body
Titanium is considered the most biocompatible metal – not harmful or toxic to living tissue – due to its resistance to
corrosion from bodily fluids. This ability to withstand the harsh bodily environment is a result of the protective oxide film
that forms naturally in the presence of oxygen.
Its ability to physically bond with bone also gives titanium an advantage over other materials that require the use of an
adhesive to remain attached. Titanium implants last longer, and much larger forces are required to break the bonds that join
them to the body compared with their alternatives.
Titanium alloys commonly used in load-bearing implants are significantly less stiff – and closer in performance to human
bone – than stainless steel or cobalt-based alloys.
Aerospace applications
Titanium weighs about half as much as steel but is 30% stronger, which makes it ideally suited to the aerospace industry
where every gram matters.
In the late 1940s the US government helped to get
production of titanium going
as it could see its potential for “aircraft, missiles, spacecraft, and other military purposes”.
Titanium has increasingly become the buy-to-fly material for aircraft designers striving to develop faster, lighter and
more efficient aircraft.
About 39% of the US Air Force’s F22 Raptor, one of the most advanced fighter aircraft in the world, is made of
titanium.
Civil aviation moved in the same direction with Boeing’s new 787 Dreamliner made of 15% titanium, significantly
more than previous models.
Two key areas where titanium is used in airliners is in their landing gear and jet engines. Landing gear needs to
withstand the massive amounts of force exerted on it every time a plane hits a runway.
Titanium’s toughness means it can absorb the huge amounts of energy expelled when a plane lands without ever weakening.
Titanium’s heat resistance means it can be used inside modern jet engines, where temperatures can reach 800℃. Steel
begins to soften at around 400℃ but titanium can withstand the intense heat of a jet engine without losing its strength.
Where to find titanium
In its natural state, titanium is always found bonded with other elements, usually within igneous rocks and sediments
derived from them.
The most commonly mined materials containing titanium are ilmenite (an iron-titanium oxide, FeTiO3)
and rutile (a titanium oxide, TiO2).
Ilmenite is most abundant in China, whereas Australia has the highest global proportion of rutile, about 40%
according to Geoscience Australia. It’s found mostly on the east, west and southern coastlines of Australia.
Both materials are generally extracted from sands, after which the titanium is separated from the other minerals.
Australia is one of the world’s leading producers of titanium, producing more than 1.5 million tonnes in 2014.
South Africa and China are the two next leading producers of titanium, producing 1.16 and 1 million tonnes, respectively.
Being among the top ten most abundant elements in Earth’s crust, titanium resources aren’t currently under threat –
good news for the many scientists and innovators constantly looking for new ways to improve life with titanium.
Titanium Forgings Shapes
Titanium forgings refer to products
manufactured by the process of shaping metal utilizing compressive forces. The compressive forces used are generally
delivered via pressing, pounding, or squeezing under great pressure. Although there are many different kinds of forging
processes available, they can be grouped into three main classes:
Forging produces pieces that are stronger than an equivalent cast or machined part. As the metal is shaped during the
forging process, the internal grain deforms to follow the general shape of the part. This results in a grain that is
continuous throughout the part, resulting in its high strength characteristics. Forgings are broadly classified as either
cold, warm or hot forgings, according to the temperature at which the processing is performed.
Iron and steel are nearly always hot forged, which prevents the work hardening that would result from cold forging. Work
hardening increases the difficulty of performing secondary machining operations on the metal pieces. When work hardening is
desired, other methods of hardening, most notably heat treating, may be applied to the piece. Alloys such as aluminum and
titanium that are amenable to precipitation hardening can be hot forged, followed by hardening. Because of their high
strength, forgings are almost always used where reliability and human safety are critical such as in the aerospace,
automotive, ship building, oil drilling, engine and petrochemical industries.
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Titanium rod and bar are made from a
corrosion-resistant material that has one of the highest strength-to-weight ratios of all metals. Due to the wear resistance,
corrosion resistance, high-temperature resistance, and non-magnetic properties of titanium rods, it is used in the main parts
of equipment, shaft body, solid parts, mixing shaft, etc.
Titanium Rods’ Characteristics
In addition, titanium rods have the characteristics of high strength, good toughness, low modulus of
elasticity, compatibility with the human body, and are widely used in the medical industry.
The forging material of the titanium rod is mainly pure titanium and titanium alloy of various compositions, and the
original state of the material is titanium rod, titanium ingot, metal powder, and liquid metal.
The ratio of the cross-sectional area of the metal before deformation to the cross-sectional area after deformation is
called the forging ratio. Proper selection of forging ratio, reasonable heating temperature and holding time, reasonable
initial forging temperature, and final forging temperature, reasonable deformation, and deformation speed is closely related
to improving product quality and reducing cost.
Generally, small and medium-sized forgings use round or square bars as blanks. If the grain structure and mechanical
properties of the bar are uniform and good, the shape and size are accurate, and the surface quality is good, it is
convenient for mass production. As long as the heating temperature and deformation conditions are properly controlled, high-
quality forgings can be forged without requiring large forging deformation.
On the aircraft, titanium alloy is mainly used to manufacture the main force members such as girders, landing
gears, hubs, and joints. Titanium alloy is mainly used to manufacture adapter rings, scraper fans, compressor discs, and
blades on the engine.
In the metalworking world, every metal part possesses its own unique set of benefits. No matter what industry
you’re in, it’s important to know the benefits of different metal components so that you can choose the part that
will be the most valuable for your specific project. One metal part that is used in various industries for it’s advantages
is titanium tubing! What are the benefits of titanium tubing? Keep reading to find out!
4 Benefits of Titanium Pipe and Tube
1. Lower Density
The density of
Titanium pipe and tube is
significantly lower than steel, copper, or nickel products. Despite their low density, they are very strong and rigid when
compared to other alloy components.
2. Resistant to Corrosion
Another benefit of utilizing titanium tubing is that titanium alloys are resistant to corrosion. This makes these
tubes an appealing option if you need a part to work efficiently in a highly corrosive environment.
3. Resistant to Chemicals
Corrosion is not the only thing that titanium tubes are resistant to. They are also resistant to chemicals. These
titanium parts can withstand different chemical compounds while still preforming effectively.
4. Great Heat Transfer Properties
Titanium tubes have great heat transfer properties thanks to its thermal conductivity and resistance. The same
can’t be said for copper and carbon steel tubes. Their resistance to heat also allows them to work successfully at
temperatures up to 600 degrees or higher.
These are just a few of the many benefits that come from utilizing titanium tubes. Because of these benefits, you can
find titanium tubing in countless important industries such as power generation, sporting goods, marine, nuclear, and paper
industries.
If you’re interested in using titanium tubes for your next project, Ferralloy, Inc. can help! We also have the
infrastructure and facilities to supply raw materials in numerous grades and forms! Visit our metalworking foundry
online today!
Titanium is sliver grey, colored transition metal found in abundance among all minerals. Titanium has high melting point
and offers very good corrosion resistant property, heat properties and strength to weight ratio. Titanium is extracted from
ores of rutile and ilmenite. Aerospace & aviation industry is the major end user of the titanium product.
Titanium is used in production of super light high speed aircrafts, satellites and spacecrafts, and ships. Apart from
aerospace & aviation, some other major end user industries of
titanium
products include paper, plastic, and paints & coatings.
Titanium products are also popular in various healthcare applications such as pacemakers, and defibrillators due to
chemical properties of titanium such as inertness to UV rays and self-cleaning properties.
Based on the different product type, the global titanium products market can be broadly categorized as titanium
concentrate, titanium tetrachloride, titanium sponge, ferrotitanium, titanium pigment and other. Based on the various
applications of the titanium product, the market can be segmented in seven broad categories namely, aerospace & marine,
industrial, medical, energy, pigments, additives & coatings, and others.
Rising demand of titanium products in aircraft carriers, defense equipments and various other chemical processing
industries such as oil and gas is driving the global titanium product market. Moreover, the recent development in cost
effective manufacturing technology coupled with superior weight-to strength ratio compare to some of the other traditional
product such as steel is expected to boost the market in upcoming years.
Unavailability of raw material, fluctuating price of input materials, and high cost of titanium product are some of
the major challenge for the titanium product market.
North America is the largest market of titanium product followed by the Europe and Asia pacific. Asia Pacific is the
fasted growing market. The major end user industry such as healthcare, power, automotive and aerospace industries of the
titanium product is growing which in turns helping the titanium product market in this region.
Some of the major companies operating in global titanium products market include, Huntsman International, DuPont, Ineos,
Iluka Resources Ltd., Sumitomo Corporation VSMPO-AVISMA Corporation., Toho Titanium Co., Ltd., RTI International Metals,
Allegheny Technologies Incorporated, Titanium Metal Corporation., Tronox Limited (U.S)., Indian Rare Earths Limited (India).,
and Sierra Rutile Limited (U.K)
Titanium is a well-known material to be characterised as flammable under certain morphologies. Titanium and its alloys
have a great affinity for oxygen and will form a native 2-7 nm TiO2 layer instantly if a clean metallic surface is
exposed to air at room temperature. This film prevents further oxidation from taking place and protects the underlying metal
powder. When heat is applied, either through a thermal source or a spark, the powder can generally or locally heat to the
point of thermal runaway or burning. The consensus mechanism of self-sustaining thermal runaway of titanium powder occurs by
means of ion diffusion through this native TiO2 film on the titanium powder [1, 2]. As the micron size of the powder
decreases, the specific surface area (in units of m2/g) increases at a rate of 6/d where d=particle diameter. In context, to
fill a typical AM machine with 45 kg of titanium powder, with an average particle size of 20 μm, this powder will have
enough surface area to cover over 3000 m2. Generally, titanium powders with a particle size < 45 μm are considered a
flammability hazard.
When describing a reaction of any metal powder, there are three categories into which each reaction may fall: 1)
stagnant, 2) freely aspirated and 3) conveyed. Stagnant powder reactions generally are a result of powder that collects
on a horizontal surface and ignition is typically from a heat source, as a more significant source is necessary to ignite a
stagnant bed of powder. When powder is dispersed in the air, the fine powders may stay aloft creating a cloud. Aspiration of
powder, and specifically titanium powder, does not automatically mean the cloud will ignite spontaneously. However, if the
temperature threshold or spark energy necessary for ignition is met, rapid oxidation of powder can occur as it mixes with
oxygen from the air. This is a result of no thermal heat sink of other powders or materials in near proximity to the powder
cloud allowing it to reach a much higher temperature and propagate to other powders, which may result in a large pressure
increase and possible explosion.
Ignition can come from a variety of sources, which will be discussed throughout this article. Thermal exposure to
temperatures of 300-700°C can cause ignition of titanium powder despite the native oxide layer (i.e., minimum ignition
temperature or MIT). Spark ignition can come from a variety of sources including static electricity build-up, electric
components and friction/impact of metal components. Titanium powder can have minimum (spark) ignition energies (MIE) of 3-30
mJ.
Powder production
After atomisation,
Titanium powder is
traditionally collected in a cyclone system. These powders are typically non-passivated. The transfer of these non-passivated
powders from the atomisation cyclone to ancillary process containers is considered to present a high risk of thermal runaway,
which may require breaking of the inert gas seal and exposure to oxygen with high potential for powder aspiration. To
overcome this problem, non-passivated powder requires exposure to air (or a reactive gas) to passivate at room temperature, a
very time consuming and potentially dangerous process. As an example, passivation of 215 kg of aluminium powder was conducted
in a powder collection canister after atomisation, requiring a 20 hour cool down (below MIT), followed by a 1.5 hour
passivation period [3]. While canisters can be isolated and moved for passivation, this process concentrates a large quantity
of nascent surface powders (i.e. highly reactive) in a confined vessel, which is not ideal.
A novel passivation approach
As a solution to this problem, Praxair Surface Technologies, Inc. uses a novel in-situ passivation process that prevents
further oxidation of the powder during exposure to air, thus minimising any exothermic reaction, thereby greatly diminishing
the possibility of thermal runaway or burning of powder. Using Praxair’s in-situ process, titanium powders are passivated
prior to reaching the cyclone collection and are deemed safe to handle after dropping below the aforementioned MIT (300-700°
C in air). This not only increases the productivity of titanium powder production, but also greatly diminishes the hazards of
the powder.
The ability to add a specific passivation layer to the titanium powder without greatly affecting the powder making
process requires the formation of an oxide shell in-situ after the powders initially solidify and descend downwards within
the atomisation chamber. The most important aspect of in-situ passivation is the generation of a layer similar (in thickness
and chemistry) to the native oxide film that will form on the surface of titanium at room temperature (i.e., a 2-7 nm thick
oxide) [4-7]. Oxide thickness becomes extremely important because of the extremely large surface area described above.
Ideally, the total oxygen content should stay below 1300 ppmw (0.13 wt.%) for a 20 μm particle, which requires a target
titanium oxide thickness of ~2-3 nm if the bulk material contains less than 1000 ppmw of O2. If the target oxide shell
thickness of 1-3 nm can be produced then no additional oxidation should take place when exposed to air at room temperature
for extended periods of time.
The post-processing of titanium powder undoubtedly will utilise electrical equipment from sieves, blenders, feeders, etc.
This challenge also presents itself to users of AM equipment. When considering electrical installations involving any
flammable substance, it is highly recommended to reference National Electrical Code, NFPA 70, particularly articles 500 to
504. These sections describe the recommended best installation practices for electrical equipment in the presence of a
hazardous material. Class II is relevant to combustible dusts (e.g., metal powders) and, within Class II locations,
there are Divisions I and II. To determine which division a process/material may fall into, the reader is directed to
read these descriptions carefully.