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Mittwoch, 24 Juni 2020 13:35

Chemical Conversion Coatings on Magnesium Alloys (Part 1)

von Dr. Anand Kumar Sharma
Geschätzte Lesezeit: 15 - 29 Minuten

There is growing demand for light metal alloys components in aerospace and automobile fields primarily to save fuel cost. Magnesium alloys promise a great potential for various applications as lightweight structural materials. This advantage stems from their low densities and high specific strength/weight ratio. Other advantages are good electrical and thermal conductivity, good impact strength, ability to dampen shockwaves, ease of forming at room temperature, weldability, buckling resistances, ductility and pressure tightness. Despite sounding like a designers‘ dream metal, magnesium has two grave drawbacks that limit their widespread applications: poor corrosion resistance and the relatively frail surface mechanical properties. Owing to the exceptional engineering properties of magnesium alloys ample attempts have been made in last few decades to develop suitable surface protection techniques. In this article the advances of chemical conversion coatings on the magnesium alloys are discussed.

Es besteht eine wachsende Nachfrage nach Komponenten aus Leichtmetalllegierungen in der Luft- und Raumfahrt und im Automobilbereich, vor allem um Treibstoffkosten zu sparen. Magnesiumlegierungen versprechen als Leichtbauwerkstoffe ein großes Potenzial für verschiedene Anwendungen. Dieser Vorteil ergibt sich aus ihren niedrigen Dichten und ihrem hohen spezifischen Festigkeits-/Gewichtsverhältnis. Weitere Vorteile sind gute elektrische und thermische Leitfähigkeit, gute Schlagzähigkeit, Fähigkeit zur Dämpfung von Stoßwellen, leichte Umformbarkeit bei Raumtemperatur, Schweißbarkeit, Knickfestigkeit, Duktilität und Druckdichtigkeit. Obwohl Magnesium wie das Traummetall der Konstrukteure klingt, hat es zwei gravierende Nachteile, die seine weit verbreitete Anwendung einschränken: schlechte Korrosionsbeständigkeit und die relativ schlechten mechanischen Oberflächeneigenschaften. Aufgrund der außergewöhnlichen technischen Eigenschaften von Magnesiumlegierungen wurden in den letzten Jahrzehnten zahlreiche Versuche unternommen, geeignete Oberflächenschutztechniken zu entwickeln. In diesem Artikel werden die Fortschritte der chemischen Umwandlungsschichten auf den Magnesiumlegierungen diskutiert.

1 Introduction

1.1 Structural Materials

Magnesium and its alloys have attracted significant research interest due to its striking characteristics such as high specific strength (density –1.74 g/cm3 and Young’s modulus –45 GPa), good thermal and electrical conductivity, vibration and shock absorption, castability, weldability, biodegradability, and biocompatibility [1–5]. Magnesium alloys are ideal materials for several applications ranging from automotive, aerospace, defence, electronics, construction and biomedical [6–10]. They are promising alternatives to aluminium alloys in aerospace/automobile industries [6, 7] and biodegradable polymers for biomedical implant applications [8–10].

Magnesium is the lightest structural metal currently available in the world. It is approximately 34 % lighter by volume than aluminium and 50 % lighter than titanium. Besides lightweight construction, a few of the other advantages that magnesium offers are excellent fatigue resistance, denting and dimensional stability, and the highest known damping capacity of any structural metal [11–17]. Dampening is a measure of the rate at which unforced vibration disappears, and it is an intrinsic property of the material. Because magnesium has the highest known damping capacity of any structural metal – as much as 10 times greater than that of steel, titanium, or aluminium-the ride on a magnesium bike is truly amazing. Vibration from the road literally disappears within the structure of the frame and never reaches the rider. Being able to ride longer and with less fatigue are the direct benefits, but the indirect benefits of magnesium might be even more important. Because vibration is not transferred through the frame, the fatigue life is nearly immeasurable. A magnesium bike will keep the exceptional initial ride qualities longer than anything else available today.

Owing to the above excellent characteristics, magnesium alloys have been extensively used in aerospace, automobile, and communications industries [18, 19]. For this same reason, magnesium is used in the high-tech world of aerospace hardware; they have discovered that magnesium offers the best platform on which to mount sensitive electronic equipment, as it is so ‘quiet’ [20–25].

Magnesium and its alloys are biodegradable and biocompatible materials, which exhibit an attractive combination of low density and high strength/weight ratio making them ideal candidates for biomedical applications like substitution and generation of tissues [26]. Temporary implants of biodegradable materials eliminate the need of a second surgery for implant removal since they are destined to corrode and dissolve post-operatively [27]. However, magnesium-based materials present poor corrosion resistance in physiological environments. Magnesium alloy AZ91D is one of the most commonly used materials in biomedical implants [28, 29].

The most critical shortcomings of magnesium and its alloys that hamper its widespread usage are weak corrosion and wear resistance and poor mechanical properties other than the strength [30–37]. Attempts have been made for addition of various alloying elements to magnesium so as to produce alloys of high strength, high creep resistance and low density.

Magnesium-lithium alloys with density of ~ 1.3 g/cm3 are the lightest structural metallic alloys known today. Addition of lithium with a relative density of 0.53, in magnesium reduces the density of alloy significantly. Furthermore, addition of ~11 % lithium converts hexagonal closed packed structure of pure magnesium to the body centred cubic lattice, markedly improving formability of the alloy [38]. The binary magnesium-lithium alloys, though light and ductile are not strong. Addition of aluminium results in considerable improvement in strength primarily due to the formation of metastable phase [39, 40].

1.2 Difficulties in Finishing of Magnesium Alloys

Magnesium is categorised as a ‘difficult metal’ for chemical treatments, because of its high chemical affinity for aqueous solutions. It reacts severely with atmospheric oxygen and water, resulting in the formation of an instant oxide-carbonate film on the surface. Unlike aluminium, this oxide film formed on magnesium is porous and is not self-healing; consequently, it does not offer protection [41]. The presence of this oxide film prevents the formation of good bonding of subsequent protection coatings on the substrate. The highly reactive nature of magnesium is clearly indicative by its position in the electrochemical series (E0 = –2.37 V). The electrochemical behaviour of magnesium in aqueous solutions can be understood from Pourbaix diagram [42], which shows that magnesium dissolves readily as Mg2+ in all solutions with a pH below 10.

Owing to the intrinsic high chemical reactivity, its corrosion resistance is very poor [30–37, 43–46]. Magnesium has the highest chemical activity among the engineering metals. Because the standard equilibrium potential of Mg/Mg2+ is negative at –2.37 vs NHE (normal hydrogen electrode), magnesium and its alloys also normally have a very negative open-circuit (or corrosion) potential (around –1.5 vs NHE) in a neutral aqueous environment. This means that magnesium alloys are readily susceptible to corrosion that can cause degradation in their mechanical properties. The metal corrodes even in moist air and in distilled water.

The situation is even more complex for magnesium alloys. The alloying constituents together with the magnesium matrix form local cathodic and anodic sites, introducing electrochemical heterogeneity. If the cathodic site has low hydrogen overvoltage, the hydrogen evolution is facilitated in these areas, and corrosion current is thus substantially increased. Alloy composition, quality and design of casting, mechanical surface finishing, etc. have to be carefully examined before proceeding to any chemical treatment. The presence of alloy impurity phases and different intermetallic phases, which differ in their chemical activity with different chemical reagents, leads to patchy deposits. If the castings have surface porosity, flaws, or oxide and flux inclusion, the quality of the coatings will be seriously affected. As the magnesium alloys are soft, the possibility of inclusions of particles of harder materials, such as silicon carbide, aluminium oxide, diamond or heavy metals, during mechanical operations such as buffing, polishing or send blasting is a potential problem. Such inclusions, flaws, porosity and presence of different phases causes electrochemical heterogeneity. Situation is alarming in particular with the magnesium-lithium alloys, because of inclusion of highly reactive lithium. Though these alloys were developed in early sixties, there is hardly any substantial industrial application of these alloys reported so far. Thus, an adequate surface modification of magnesium alloys is absolutely necessary to enhance their corrosion resistance before being applied to a working environment.

Surface finishing is employed as an ideal means for improving one or more surface properties, chemical, mechanical, electrical or optical. These are used for preventing corrosion; providing better adhesion for paints, lubricants, and adhesives; improving micro hardness; reducing friction on sliding surface; producing a solid film lubricant to prevent cold welding in space conditions; providing adequate optical surface for thermal control application, etc. [47–55]. In last few decades several surface modifications have evolved for corrosion protection of magnesium alloys, these methods include variety of processes such as the chemical immersion, the electrochemical conversion and plating, the ion implantation, the laser treatments, etc. [56–61]. In the present article, methods of chemical conversion coatings developed on magnesium alloys for variety of function applications are discussed. Emphasis is made for the processes that are effective for common applications and are easily adoptable by the user industries. For this reason, the studies related to the influences of additives / inhibitors, that are often not very conclusive are deliberately not covered in this article.

1.3 Thermal Control Applications

A spacecraft in orbit undergoes extreme temperature cycling due to direct sun load on one side and deep cold space (temperature – 270.4 °C) on the other. This causes a large thermal gradient between the sunlit and shadowed sides of the vehicle. The various subsystems of the spacecraft can, however, work at their fullest efficiency within the specified temperature limits.

We live in the world of “room temperature” technology. Most of the equipment and materials work in their fullest efficiency around this temperature. Equipment on Earth having a tendency to run too cold or too hot may be readily brought back to acceptable operating temperatures through heat exchange with the atmosphere. In space, heat exchange is restricted to radiation, which is a poor substitute for convection. Under these circumstances, the challenge in spacecraft thermal design is to achieve the proper in-orbit operational temperatures for different components of spacecraft.

If we consider a spacecraft far away from earth’s atmosphere and assume that it does not have any internal power dissipation, the steady state temperature of spacecraft can be expressed by the following energy balance equation [62]:

"$SA_p α = σεAT^4  or  T = \frac{SA_pα}{σAε}^¼$"

Where, T is the absolute temperature of the spacecraft in K, S is the solar constant (mean value 1,353 Wm–2), σ is the Stefan-Boltzmann constant (56.7 × 10–9 Wm–2K–4), Ap is the projected area of the spacecraft in m2 and A is the total surface area of the spacecraft in m2, α is the solar absorptance and ε is the thermal emittance of the exposed surface. Because S, σ, Ap and A are constant in this relationship, it can be seen that the temperature of a given area of the spacecraft is directly controlled by the α/ε ratio. Here, the term ‘absorptance’ refers to all solar radiation (X-ray, ultraviolet, visible, infrared, radio frequency, etc.), whereas the term ‘emittance’ is restricted to the infrared range because thermal radiation occurs mainly in the infrared region.

Thermal control techniques are broadly grouped into passive and active. Passive thermal control techniques are preferentially adopted for the thermal control of spacecraft. The passive system does not involve any relative movement of its parts and does not require external power for operation. This eliminates the possibility of its failure. The passive thermal control system utilizes known optical properties of surface to achieve the required thermal control. Active thermal control systems require external power for their operations and/or involve the moving parts, for example electrical heaters, mechanical refrigerators, thermostatic louvers, pumped fluid loops, etc. The passive thermal control methods are used when simplicity, cost and reliability are the key design factors [63, 64].

Thus, the surface finishing of components with known optical characteristics plays an important role in the thermal management of spacecraft with high reliability. The low α/ε coatings are utilized to minimise the temperature while higher α/ε to raise the temperature of components. In a spacecraft some of the packages in operation generate enormous heat while others face deep cold space. The flat absorber high emittance black coatings are the best choice in such areas to reduce the large temperature gradient and maintain overall uniform on-orbit temperature across all the electronic packages. The low ε coatings on the other hand are applied to those internal components of spacecraft where radiative isolation from surrounding environment is required.

The finishing used in space technology, however, requires higher standards and better control than those used for ground applications, because an on-orbit spacecraft is not approachable for repair and space conditions are very severe. The coatings designed for space missions have to withstand extreme aerodynamic heating, acceleration, shock, vibration and acoustic noise during space flight, and ultrahigh vacuum, bombardment by high energy particles (electrons and protons) and extreme temperature cycling in the orbit. The application of defective coatings not only seriously affects the performance of a particular subsystem but also increases the probability of the failure of the entire mission by damaging it permanently. The space worthiness of the coating is evaluated by the simulated environmental tests, viz, humidity, thermal cycling, thermovacuum and radiation tests. Further evaluation of coating is carried out by outgassing test, measurement of optical, electrical properties and any other test based on the functional requirements.

Solar selective coatings used for solar water heaters, solar power generators and allied equipment also work with the similar principle. However, unlike space, for ground application as there is environment present; all mode of heat transfer, viz., convection, conduction and radiation are to be considered.

2 General Cleaning and Pre-treatment Procedures

As all other metallic objects being prepared for finishing, a clean surface of substrate material is necessary for adherent coating. Therefore, all surface contaminants such as oil, grease, dirt, die forming components, surface oxides, etc. must be removed. This requires establishment of suitable cleaning cycle depending on the condition of the object and nature of the contaminants to be removed. In some cases, it may be prudent to remove the previous surface treatment that was applied for temporary protection. The general cleaning and pre-treatment methods described herein are derived from the standard literature [65–71] and based on authors own work in the field. The methods and sequence specific to particular alloy or for precise end finishing are further described in detail.

2.1 Mechanical Cleaning

The methods of mechanical cleaning of magnesium alloys are similar to those used on zinc and aluminium alloys. These includes blasting, sanding and brushing. Stainless steel or aluminium wire brushes should be used. Aluminium wool and aluminium oxide papers also give good results. Regular steel wool and brushes as well as silicon carbide cloth should not be used. When blasting method of any type employed there is danger of embedding surface contaminants which will greatly increase the basic surface corrosion rate. In such cases subsequent acid pickling must be used to each up to 50 µm from the surface prior to the application of any coating.

2.2 Solvent Cleaning

Solvent cleaners are employed to remove abnormal amount of grease oil from the job. These are also used for cleaning of finished products which have been soiled in handling. Solvent cleaning prevents a rapid build-up of oil and grease in the subsequent alkaline cleaner and reduces the time in this operation. Vapor decreasing, ultrasonic cleaning or immersion methods may be employed using chlorinated solvents, hydrocarbons and alcohols as a solvent. Emulsion cleaners can also be used. These cleaners are essentially a mixture of emulsifying agents and hydrocarbon solvents in which it is possible to water rinse the solvent and contaminants from the surface after cleaning, by dip or spray method.

2.3 Alkaline Cleaning

Magnesium unlike aluminium, is not appreciably attacked by caustic solutions. Therefore, heavy duty alkaline cleaners high in caustic can be used. These solutions are particularly beneficial when old chromate type of coating as well as heavy oil and grease are to be removed. The following chemical formulation provides satisfactory results for most of the magnesium alloys:

Sodium hydroxide, NaOH 60 g/L
Trisodium orthophosphate,
Na3PO4 · 12H2
10 g/L
Wetting agent (soap or Nacconal®) 0–0.5 g/L
Temperature  80–100 °C
Time 3–20 minutes
Tank material steel

 

Higher caustic soda concentrations are used to remove burned-on die lubrication and the lower concentration for special alloys high in zinc and zirconium that are less resistant to strongly alkaline solutions. If the solution is to be used as a soak cleaner, wetting agent is added and the job is agitated to obtain uniform cleaning.

Electro cleaning shortens the cleaning time considerably, the same solution can be used except that the presence of wetting agent is undesirable. The work is made cathode and a current density of 2–4 Adm–2 is employed for 1–5 minutes. No agitation of work is required.

A mild alkaline cleaner (de-oxidizer) of following composition can be used to remove low scale oil and grease, where the jobs are only slightly contaminated.

Trisodium pyrophosphate, Na3PO4 · 12H2O 40 g/L 
Borax, Na2B4O 770 g/L
Sodium fluoride, NaF 20 g/L
Temperature 75–80 °C
Time  2–5 minutes
Tank material steel

 

2.4 Acid Pickling

Acid pickling is required to remove the oxide layer and flux from the castings; previously applied coatings; burned-on drawings and forming lubricants or other water soluble and un-emulsifiable substances. The dimensional changes associated with acid pickling are high since these solutions dissolve the base material as well. Numerous pickling solutions have been used in the past for magnesium alloys but only those which are most commonly used are described here.

Chromic acid pickling is useful for close tolerance parts to remove superficial oxide. The parts can be cleaned by immersion in a solution of following composition:

Chromium trioxide, CrO3 180 g/L
Temperature 25–100 °C
Time 1–15 minutes
Tank material lead, stainless steel (SS), aluminium 1100 or vinyl lined steel


Chromic acid-ferric nitrate bright pickle is effective to all common magnesium alloys and forms. It produces a chemical polishing effect proving a smut free bright surface. The parts can be dipped or sprayed with the solution of following composition:

Chromium trioxide, CrO3  180 g/L 
Ferric nitrate, Fe(NO3)3 · 9 H2O 40 g/L
Potassium Fluoride, KF 2–7 g/L
Temperature 20–30 °C (room temperature)
Time 15 seconds to 3 minutes
Tank material stainless steel-316 or vinyl lined steel

In this solution approximately 4 µm of surface is removed per minute. Increasing the fluoride contents tend to increase the reactivity. Low fluoride concentration is preferred for wrought products and high fluoride content for castings.

Chromic acid-sodium nitrate bright pickle is commonly used for wrought magnesium alloys that are low in aluminium contents. The burn-on graphite lubricants from hot formed sheet parts can be effectively cleaned prior to arc or gas welding.

Chromium trioxide, CrO3  180 g/L
Sodium nitrate, NaNO3 30 g/L
Temperature 20–30 °C (room temperature)
Time 15 seconds to 3 minutes
Tank material stainless steel-316 or vinyl lined steel

Increasing the chromic acid and decreasing the sodium nitrate provides best results for basket pickling of small parts. A pH range of 0.5 to 0.7 is most effective. When the pH is increased above 1.7, it should be lowered by addition of chromium trioxide.

Aetic acid-sodium nitrate pickle is primarily used for the removal of mill scale oxides from wrought alloys and non-aluminium magnesium castings. A metal removal of approximately 25 µm per minute from the job surface is expected by this pickling.

Glacial acetic acid, CH3COOH  200 ml/L 
Sodium nitrate, NaNO3 50 g/L
Temperature  20–30 °C (room temperature)
Time 15 seconds to 1 minutes
Tank material aluminium alloy 1100, ceramic, SS 316 or rubber lined steel

3 Chemical conversion coatings

Chemical conversion coatings are one of the most common surface modification techniques that provide a barrier between metal and its surrounding environment. The term conversion coating is used to describe the coatings where part of the metal surface is converted into the coating with a chemical or electrochemical process. The coatings thus formed are composed of chemically inert inorganic compounds that provide corrosion inhibition.

In earlier days, hexavalent chromium compounds were widely used for producing conversion coatings on magnesium alloys. However, in the recent years, efforts have been made to reduce the use of Cr6+ as it is found to be carcinogenic. Some alternative methods, such as rare earth metal conversion coatings, stannate coating, molybdate conversion coating, photo electrochemical nucleation, etc. have been investigated as the eco-friendly corrosion protection coatings on the magnesium and its alloys [72, 73].

Various chemical conversion coatings such as chrome pickling, dichromate treatment, phosphate coating, chrome-manganese conversion coating or galvanic black anodizing have been used for magnesium alloys to give corrosion protection in mild corrosive environments [30]. The corrosion resistance of some of these processes can be further improved by application subsequent coat of paint, lacquer or sol-gel coatings. Some of the electrochemical conversion coatings processes, viz, modified caustic anodizing, modified acid fluoride anodizing (MAFA) and micro arc oxidation (MAO) provide excellent long-term surface protection by themselves.

3.1 Chemical Immersion Processes

Chemical immersion processes are primarily intended for a temporary protection, i. e., for short storage or shipment or to provide a good base for subsequent protective coating or paint. In some cases, these treatments may provide adequate corrosion protection by themselves e. g., interior parts of engine that are normally covered with oil which adds to protection.

3.1.1 Chrome pickle

Chrome pickle is the most commonly used chemical treatment for magnesium alloys. The treatment can be carried out by dipping, spraying or by application of brush. As this treatment removes up to 15 µm surface per minute, it is not recommended for close tolerance parts. Composition A is recommended for wrought products while

composition B (modified chrome pickle) is used for castings:

 
Sodium dichromate, Na2Cr2O7 · 2H2 125 g/L 25 g/L
Nitric acid (70 % V/V), HNO3  190 ml/L 125 ml/L
Sodium acid fluoride, NaHF2 --- 15 g/L
Aluminium sulphate, (Al2SO4)3 · 14H2O --- 10 g/L
Temperature  20–30 °C (room temperature)
Tank material poly vinyl chloride (PVC), polypropylene (PP)


A standard 1-minute time is used for all the alloys except for die castings where the time is reduced to 20–30 seconds. The transfer time between treatment and cold-water rinsing to be kept minimum (5–15 seconds) to avoid the formation of loose powdery coatings. The colour of the coating is matt grey to yellow-red iridescent with a degree of fine surface etching for good paint adhesion. Large articles or repair areas can be treated by brush applications, but the colour obtained is not as uniform as obtained by dip or spray processes.

To improve the corrosion resistance on wrought products the chrome-pickle treatment after cold water rinsing should be immediately followed by the sealing. The sealing is carried out in boiling dichromate-fluoride solution (as described later under dichromate treatment) for 30 seconds. Sealing of the old chrome-pickled film is not recommended since the aging of film prevents proper sealing.

3.1.2 Dichromate treatment

Dichromate treatment is the most common dip chemical process for magnesium alloys used today and it provides good corrosion protection. This treatment has no significant effect on dimensions and is normally applied on machined parts prior to painting. The appearance varies from light to dark brown depending on the alloy composition. The process sequence for dichromate treatment involve solvent degreasing, alkaline cleaning, fluoride treatment and dichromate coating.

Fluoride treatment is carried out by immersing the work in 280 ml/L hydrofluoric acid (40 % V/V) solution at room temperature. All magnesium alloys except aluminium zinc (AZ) are immersed for 5 minutes. A short dip for 30 seconds is used for AZ magnesium alloys, otherwise the passive fluoride film produced tend to retard the formation of subsequent dichromate coating. An alternative fluoride treatment using 50 g/L of sodium, potassium or ammonium acid fluoride or mixture of these salts may be used. The parts are immersed in this solution for 15 minutes and then rinsed in cold water. This solution does not attack aluminium inserts, rivets, etc. that are present in magnesium job.

After fluoride treatment the dichromate treatment is applied by immersing the parts in the following solution:

Sodium dichromate, Na2Cr2O7 · 2H2 150 g/L
Calcium or magnesium fluoride, CaF2/MgF 22.5 g/L
Temperature 90–100 °C (near or at boiling temperatures)
Time 30 minutes
Tank material SS, PP

 

The presence of calcium or magnesium fluoride assists in the chromate film formation. They are only slightly soluble and thus their concentration need not be controlled. They can be conveniently suspended in the solution in cloth bags or the excess can be added in tank so that the bath remains saturated with them. However, it must be noted that the high free fluoride concentration renders the bath inoperable, hence it must not exceed 0.2 %. After dichromate treatment, the parts are rinsed thoroughly in cold water and then in hot water to facilitate drying.

3.1.3 Dilute Chromic Acid Treatment

This is the least expensive treatment on magnesium alloys. It can be applied by brush, spray or dip methods. Better corrosion protection is afforded then with phosphate treatment although the paint base properties are similar. It is less critical to apply than the chrome-pickle for touch up repair work on previously coated surfaces as it is not corrosive if entrapped between faying areas. The following composition is employed:

 

Chromium trioxide, CrO3 180 g/L
Calcium sulphate, CaSO4 · 2 H2O 30 g/L
Temperature 20–30 °C (room temperature)
Time 30–60 seconds for dip process and 1 to 3 minutes for brush or spray applications
Tank material SS 316 or vinyl lined steel

 

The chemicals are added in water and stirred vigorously for about 15 minutes to ensure the saturation of solution with calcium sulphate. For optimum results surface be kept wet with solution until a brassy iridescent film is formed. Unlike chrome pickle the time between pickling and cold-water rinsing is not critical. When water rinsing is not possible sponge drying of the drain off liquid at the edges of works is sufficient. For machined AZ31B alloy components, a very dilute solution of the following composition can be effectively used:

Chromium trioxide, CrO3  10 g/L 
Calcium sulphate, CaSO4 · 2 H2O 7.5 g/L
pH 1.2
Temperature 20–30 °C (room temperature)
Time 30–60 seconds

 

-to be continued-

References

[1] S. Bender; J. Göllner; A. Heyn; C. Blawert; P.B. Srinivasan: Corrosion and surface finishing of magnesium and its alloys in Fundamentals of magnesium alloy metallurgy, M.O. Pekguleryuz, K.U. Kainer, A.A. Kaya, (Editors), Woodhead Publishing (2013) 232–265
[2] K.K. Sankaran; R.S. Mishra: Metallurgy and design of alloys with hierarchical microstructures, Elsevier, Chapter 7 – Magnesium alloys (2017) 345–383
[3] M.M. Avedesian; H. Barker: Magnesium and magnesium alloys, ASM International (1999)
[4] G. Song; A. Atrens: Adv. Eng. Mater, 5(2003) 837–858
[5] W.H. Sillekens; N. Hort: Magnesium and magnesium alloys, structural materials and processes in transportation, Wiley Online Library (2013)
[6] B.L. Mordike; T. Ebert: Mater. Sci. Eng. A, 302(2001) 37–45
[7] G. Bhargava; F. Allen: Self-healing, chromate-free conversion coating for magnesium alloys, J. Met. Finish. Soc. Jpn, 110(20129 32–38
[8] H. Hornberger; S. Virtanen; A.R. Boccaccini: Acta Biomater, 8(2012)7, 2442–2455
[9] F. Witte: The history of biodegradable magnesium implants: a review, Acta Biomater, 6(2010) 1680–1692
[10] N. Li; Y. Zheng: Novel magnesium alloys developed for biomedical application: a review, J. Mater. Sci. Technol, 29(2013) 489–502
[11] J. Liang; L. Hu; J. Hao: Appl. Surf. Sci, 253(2007) 4490–4496
[12] Y. Zhang; C. Yan: Surf. Coat. Technol, 201(2006) 2381–2386
[13] D. Jun; J. Liang; L. Hu; J. Hao; Q. Xue: Trans. Nonferrous Met. Soc. China, 17(2007) 244–249
[14] J. Liang; B. Guo; J. Tian; H. Liu; J. Zhou; T. Xu: Appl. Surf. Sci, 252(2005) 345–351
[15] Y.K. Lee; K. Lee; T. Jung: Electrochem. Commun, 10(2008) 1716–1719
[16] Y. Cui; J. Li; Y. Li; Y. Koizumi; A. Chiba: Mater. Sci. Eng. A., 708(2017) 104–109
[17] J. Zhang; R.J. Perez, E.J. Lavernia: J. Mater. Sci, 28(1993) 2395–2404
[18] X. Zhang; Z. Zhao; F. Wu; Y. Wang; J. Wu: J. Mater. Sci, 42(2007) 8523–8528
[19] A.A. Luo: Applications: Aerospace, automotive and other structural applications of magnesium in Fundamentals of magnesium alloy metallurgy, M.O. Pekguleryuz, K.U. Kainer, A.A. Kaya, (Editors), Woodhead Publishing (2013) 266–316
[20] R. Uma Rani; V. Maria Shalini; H.K. Thota; A.K. Sharma: J. Coat Technol. Res, 10(2013)5, 707–715
[21] R. Ambat; W. Zhou: Surf. Coat. Technol, 179(2004) 124–134
[22] H. Friedrich; S.J. Schumann: J. Mater. Process Tech, 117(2001) 276–281
[23] E. Aghion; B. Bronfin; D. Eliezer: J. Mater. Process. Tech, 117(2001) 381–385
[24] S.R. Agnew; J.F. Nie: Scr. Mater, 63(2010) 671–673
[25] X. Chen; G. Li; J Lian; Q. Jiang: Appl. Surf. Sci, 255(2008) 2322–2328
[26] A.L. Rudd; C.B. Breslin; F. Mansfeld: Corros. Sci, 42(2000) 275–288
[27] Y.F. Zheng; X.N. Gu; F. Witte: Biodegradable metals. Mater. Sci. Eng. R. 77(2014) 1–34
[28] G. Ballerini; U. Bardi; R. Bignucolo; G. Ceraolo: Corros. Sci, 47(2005) 2173–2184
[29] A.P. Loperena; I.L. Lehrm; S.B. Saidman: IntechOpen (2018) 79329, https://doi.org/10.5772/intechopen.79329
[30] J. Gray; B. Luan: J. Alloys Compd, 336(2002) 88–113
[31] D. Mehta; S. Masood; W. Song: J. Mater. Process. Tech, 155(2004) 1526–1531
[32] R. Gadow; D. Scherer: Surf. Coat. Technol, 151(2002) 471–477
[33] P.J. Blau; M. Walukas: Tribol. Int, 33(2000) 573–579
[34] N. Yamauchi; K. Demizu; N. Ueda; N. Cuong; T. Sone; Y. Hirose: Surf. Coat. Technol, 193(2005) 277–282
[35] R. Zhang; S. Zhang; S. Duo: Appl. Surf. Sci, 255(2009) 7893–7897
[36] L. Liu; M. Schlesinger: Corros. Sci, 51(2009) 1733–1737
[37] G. Song; A. Atrens; X. Wu; B. Zhang: Corros. Sci, 40(1998) 1769–1791
[38] C.R. Chakravorthy: Bull. Mater. Sci, 17, No. 6(1994) 733–745
[39] J.C. McDonald: ASM Trans, 61, No. 3(1968) 505–518
[40] J.C. McDonald: J. Inst. Metals, 97, No.12(1969) 353–362
[41] G.T. Parthiban; S. Muralidharan; N. Palaniswamy; K. Chittukala; D. Chanthraleka; A. Shamitha Begum: J. Electrochem. Soc. India, 54(2005) 129–134
[42] M. Pourbaix: Atlas of electrochemical equilibria in aqueous solutions, National Association of Corrosion Engineers, (1974) 139
[43] L. Li; Y. Cheng; H. Wang; Z. Zhang: Trans. Nonferrous Met. Soc. China, 18(2008) 722–727
[44] E. Ghali: Corrosion resistance of aluminium and magnesium alloys-understanding, performance and testing,1st Edition, Wiley, Hoboken, NJ (2010)
[45] H. Inoue; K. Sugahara; A. Yamamoto; H. Tsubakino: Corros. Sci, 44(2002) 603–610
[46] G.L. Song; A. Atrens: Adv. Eng. Mater, 1(1999) 11–33
[47] A.K. Sharma: Trans. SAEST, India, 30, No. 12(1995) 1–13
[48] A.K. Sharma: Surf. Eng, 21, No. 3(2005) 249–253
[49] A.K. Sharma: Trans. MFAI, 11(2002) 133–140
[50] R. Uma Rani; A.K. Sharma; S.M. Mayanna; H. Bhojraj; D.R. Bhandari: Surf. Eng, 21 No. 3(2005) 198–203
[51] V. Saxena; R. Uma Rani; A.K. Sharma: Surf. Coat. Technol, 201, No. 3–4(2006) 855–862
[52] V. Saxena; R. Uma Rani; A.K. Sharma: Galvanotechnik, 97(2006)4, 827–840
[53] A.R. Shashikala; R. Uma Rani; A.K. Sharma; S.M. Mayanna: Galvanotechnik, 97(2006)10, 2387–2400
[54] A.R. Shashikala; A.K. Sharma; D.R. Bhandari: Sol. Energy Mater. Sol. Cells, 91(2007)7, 629–635
[55] A.K. Sharma; N. Sridhara: Adv. Space Res, 50(2012) 1411–1424
[56] H. Meifeng; L. Lei; W. Yating; T. Zhixin; H. Wenbin: Corros. Sci, 50(2008) 3267–3273
[57] T. Lei; C. Ouyang; W. Tang; L.-F. Li; L.-S. Zhou: Surf. Coat. Technol, 204(2010) 3798–3803
[58] P. Liu; X. Pan; W. Yang; K. Cai; Y. Chen: Mater. Lett, 75(2012) 118–121
[59] I. Nakatsugawa; R. Martin; E.J. Knystautas: Corrosion, 52(1996) 921–926
[60] L.A. Dobrzanski; J. Domaga; T. Tanski; A. Klimpel; D. Janicki: Archives Mater. Sci. Eng, 30(2008) 113–116
[61] S. Shrestha; B.D. Dunn: Surface engineering of light alloys: Aluminium, magnesium and titanium alloys, H. Dong (Editor), CRC Press, Woodhead Publishing Ltd, (2010) 603–641
[62] B.N. Agarwal: Design of geosynchronous spacecrafts. Prentice Hall, Englewood, (1986) 273, 281
[63] D.G. Gilmore: Spacecraft thermal control handbook, Vol. I: Fundamental technologies, 2nd Edition, The Aerospace Corporation Press (2002)
[64] F. Anvari; F. Farhani; K.S. Niaki: Comparative study on space qualified paints used for thermal control of a small satellite, Iranian J. Chem. Eng, 6(2009)2, 50–-62
[65] J.E. Hillis: ASM Hand book on surface engineering, Surface engineering of magnesium alloys, C.M. Cotell, J.A. Sprague, F.A. Smidt Jr., (Editors): ASM International, 5(1994) 819–834
[66] W. Canning: Canning handbook of electroplating, The surface finishing of magnesium, W. Canning & Co. Ltd., 21st Edition (1989) 722–727
[67] H.K. DeLong: Anodizing and surface conversion treatments for magnesium in Electroplating engineering handbook, L.J. Durney (Editor), Van Nostrand Reinhold, New York (1984) reprinted (2000) 410–419
[68] F. Czerwinski (Editor): Magnesium alloys corrosion and surface treatments, IntechOpen Limited, London (2011)
[69] Metal finishing guide book and directory, American Electroplating Society, Volume 93(1995)
[70] F.A. Lowenheim (Editor): Electroplating: Fundamentals of surface finishing, McGraw-Hill (1978)
[71] D. Höche; A. Nowak; T. John-Schillings: Surface cleaning and pre-conditioning surface treatments to improve the corrosion resistance of magnesium (Mg) alloys in Corrosion prevention of magnesium alloys, G.L. Song (Editor), Woodhead Publishing Limited (2013) 87–109
[72] L. Anicai; R. Masi; M. Santamaria; F. Di Quarto: Corros. Sci, 47(2005) 2883–2990
[73] A.R. Shashikala; R. Umarani; S.M. Mayanna; A.K. Sharma: Int. J. Electrochem. Sci, 3(2008)9, 993–1004

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  • Ausgabe: 6
  • Jahr: 2020
  • Autoren: Dr. Anand Kumar Sharma

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