Quality of Life
Titanium improves the quality of individual lives when it is used for medical and dental implants, prosthetic devices, eyeglasses and even lightweight wheelchairs. World product shipments are estimated at over 60,000 metric tons, of which at least 50% was used in applications other than aerospace.
Bio-Compatible
Titanium is the most bio-compatible of all metals due to its corrosion resistance, strength and low modulus. This excellent level of biocompatibility as determined by in vitro cell culture tests has been confirmed by in vivo observations directly in numerous patients with total joint prostheses. The unwanted biological effects are about 10 times less frequent in patients with titanium implants than in those patients with implants made from other alloys. Where Ti-6Al-4V has been used, the low concentration of titanium, vanadium and aluminum in body fluids from patients with heavy wear on the prosthesis demonstrates the low dissolution rate of the wear particles.
Titanium is thus widely used for implants, surgical devices and pacemaker cases. Its use for hip replacements and other joints, has been well established for some 40 years. Titanium not only fosters Osseointegration (joins with bones & tissues), it is non-magnetic and non-radio opaque. Titanium instruments are used for micro-surgical operations and in military light weight field trauma relief kits.
Some prostheses are engineered with roughened surfaces or porous coatings (such as hydroxy-apaptite) which hasten the bonding of titanium with adjacent hone. Surface treatment, including shot peening, nitriding and diamond like coatings may be used to provide enhanced wear resistance.
Commercially pure titanium. Ti-6Al-4VELI and Ti-6Al-7Nb (367) continue to be the most frequently specified materials for prosthetic use. Earlier concerns about release of vanadium and/or aluminum from alloys have been largely resolved. Commercially pure titanium and most alloys are effectively nickel free and will not cause nickel dermatitis.
Titanium—A Global Material of Choice
Titanium in the 21st century has emerged as a high-performance metal specified for demanding industrial, medical and commercial applications throughout the world. A wide spectrum of applications verify titanium’s strong global profile: aerospace engine components and structural components built in North America and Europe; desalination systems in the Middle East; modern, high-profile architectural structures in Asia; offshore oil and gas exploration throughout the world; and an array of chemical processing and infrastructure projects in all major international markets.
Further evidence of titanium’s global presence can be found in the recent expansion of metal and sponge production capacity at sites in Russia, China, Japan and the United States. And industry experts from the four corners of the world gather at the annual TITANIUM conference and exhibition, sponsored by the International Titanium Association, bringing news of titanium developments and success stories. Titanium indeed has come of age as a global material of choice.
Low Modulus of Elasticity
Titanium’s low modulus means excellent flexibility and strong spring back characteristics. This promotes its use in various springs for aircraft and valves, where a modulus half that of steel, but a strength equivalent to steel allows a titanium spring to be half as large and heavy. This property also benefits auto parts (which must absorb shock), medical implants (that must move with the body), architecture (where roofs must resist hail stones), as well as recreational gear (golf clubs, tennis racquets, mountain bikes and skis).
Food and Pharmaceutical
Titanium demonstrates excellent corrosion resistance, not only to various food products and pharmaceutical chemicals, but also to the cleaning agents utilized. As equipment life becomes a more critical factor in financial evaluations, titanium equipment is replacing existing stainless steel apparatus. Titanium can also eliminate the problems of metal contamination.
Titanium is thus widely used for implants, surgical devices and pacemaker cases. Its use for hip replacements and other joints, has been well established for some 40 years. Titanium not only fosters Osseointegration (joins with bones & tissues), it is non-magnetic and non-radio opaque. Titanium instruments are used for micro-surgical operations and in military light weight field trauma relief kits.
Some prostheses are engineered with roughened surfaces or porous coatings (such as hydroxy-apaptite) which hasten the bonding of titanium with adjacent hone. Surface treatment, including shot peening, nitriding and diamond like coatings may be used to provide enhanced wear resistance.
Commercially pure titanium. Ti-6Al-4VELI and Ti-6Al-7Nb (367) continue to be the most frequently specified materials for prosthetic use. Earlier concerns about release of vanadium and/or aluminum from alloys have been largely resolved. Commercially pure titanium and most alloys are effectively nickel free and will not cause nickel dermatitis.
Titanium’s remarkable combination of metallurgical and physical characteristics can generate an array of benefits for demanding industrial and commercial applications in global markets. It’s most successfully employed when the initial design exploits its unique attributes, rather than when it’s merely substituted for another metal. In some demanding applications, like jet engines and medical implants, titanium allows the item to perform to its maximum potential.
Titanium has been used in medical applications since the 1950’s. It’s the most biocompatible of all metals and in prosthetic and joint-replacement devices it actually allows human bone growth to adhere to the implants so they last longer. Pacemaker cases are made from titanium because it resists attack from body fluids, is lightweight, flexible and non-magnetic. Artificial heart valves are also made of titanium.
Anodizing
Titanium is one member of a family of metals (that includes niobium and tantalum) that color anodizes because it is “reactive”, i.e. it reacts when excited by heat or electricity in an electrolyte by creating a thin oxide layer at the surface. The oxide layer presents itself in color due to an interference phenomenon. This layer is a very thin, transparent coating that derives its ‘color’ when white light reflects off the base metallic surface, only to be “interfered with” within the coating. Some frequencies of light waves escape and recombine with surface light to be either reinforced or cancelled out—producing the color we see.
Anodized coatings can be applied to titanium for a number of reasons: General color-coding, Product/part identification, Material Identification, Size identification, Corporate color matching, Product appeal enhancement, Aesthetics, and Enhanced properties.
Titanium anodizing provides some products with improved properties compared to those in a raw or “unfinished” state. Test data validate numerous mechanical benefits, and observation with a 10x eyepiece reveals the leveling effects of the process. Scars from machining and/or deburring are ‘leveled’ into a continuous, smoother, gray-colored surface. The two most common types of treatment are Type II anodizing and color anodizing. Type II Anodizing Anodic treatment of titanium and its alloys is typically performed in accordance with SAE International’s AMS 2488 Standard. The process is covered under an Aerospace Material Specification, as it was first developed for treatment of parts associated with the air and space industries. Advantages associated with the Type II titanium anodizing process include increased lubricity, anti-galling, and increased fatigue strength. As these advantages have become increasingly apparent, the popularity and acceptance of this coating have grown considerably within the medical device industry, especially in terms of its applicability to the finishing of orthopedic implants. The anodization process accelerates the formation of an oxide coating under controlled conditions to provide the desired result. Since the coating is biocompatible as well as non-toxic, the process lends itself to achieving drastic improvement in implant performance. The coating is created using various electrolytes, whereby the devices are made positive (anodic), with a corresponding negative (cathodic) terminal attached to a D.C. power supply. As the process creates a penetrating coating, there is no measurable dimensional change when measured with a micrometer accurate to 0.0001 inch (2.5 µm). Quality inspection (100% visual) is performed on completed parts. Controlling factors that impact the end result include: cleaning and surface preparation; solution limits and control; voltage limits and control; temperature limits and control; and post-anodizing treatment and packaging.
Products for which titanium anodization is applicable range from orthopedic and dental implants, to undersea mateable connectors, to aerospace components. Within the orthopedic industry, products for which this type of treatment is often applied include bone plates and screws, intramedullary nails and rods, spine “cages,” and other hardware commonly associated with trauma or spinal surgery.
ITA’s Medical Technology Committee Members:
Colin McCracken, Oerlikon Metco (Canada) Inc. (Committee Chair) Patrick Becker, Hartmann Materials, a Bibus Group Company Eric Baum, Laboratory Testing Inc. Art Kracke, AAK Consulting L.L.C. Stephen Smith, Edge International
Tom Zuccarini, Vested Metals International, LLC
|