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70-601: The Navy Cross is bestowed by the Secretary of the Navy and may also be awarded to members of the other armed services, and to foreign military personnel while serving with the U.S. Naval Service. The Navy Cross was established by Act of Congress ( Public Law 65-253 ) and approved on February 4, 1919. The Navy Cross was instituted in part due to the entrance of the United States into World War I . Many European nations had

140-613: A 3-step process: sulfuric acid anodizing, electrochemical modification of the anodic pore, and metal (tin) deposition. Sealing is the final step in the anodizing process. Acidic anodizing solutions produce pores in the anodized coating. These pores can absorb dyes and retain lubricants but are also an avenue for corrosion. When lubrication properties are not critical, they are usually sealed after dyeing to increase corrosion resistance and dye retention. There are three most common types of sealing. Anodized aluminium surfaces that are not regularly cleaned are susceptible to panel edge staining ,

210-441: A coating that is 2 μm thick will increase the part dimensions by 1 μm per surface. If the part is anodized on all sides, then all linear dimensions will increase by the oxide thickness. Anodized aluminium surfaces are harder than aluminium but have low to moderate wear resistance, although this can be improved with thickness and sealing. A desmut solution can be applied to the surface of aluminium to remove contaminates. Nitric acid

280-777: A degree self-healing. They are harder to dye and may be applied as a pretreatment before painting. The method of film formation is different from using sulfuric acid in that the voltage is ramped up through the process cycle. Sulfuric acid is the most widely used solution to produce an anodized coating. Coatings of moderate thickness 1.8 μm to 25 μm (0.00007" to 0.001") are known as Type II in North America, as named by MIL-A-8625, while coatings thicker than 25 μm (0.001") are known as Type III, hard-coat, hard anodizing, or engineered anodizing. Very thin coatings similar to those produced by chromic anodizing are known as Type IIB. Thick coatings require more process control, and are produced in

350-721: A number of commands annually for achievements in such areas as environmental quality , environmental cleanup , natural resources conservation , cultural resources management , pollution prevention , and recycling . The chief of naval operations and the commandant of the Marine Corps have their own separate staffs, the Office of the Chief of Naval Operations (also known by its acronym OPNAV) and Headquarters Marine Corps . (Post of Secretary of Marine created but remained vacant) Anodizing Anodizing

420-494: A porous surface which can accept dyes easily. The number of dye colours is almost endless; however, the colours produced tend to vary according to the base alloy. The most common colours in the industry, due to them being relatively cheap, are yellow, green, blue, black, orange, purple and red. Though some may prefer lighter colours, in practice they may be difficult to produce on certain alloys such as high-silicon casting grades and 2000-series aluminium-copper alloys . Another concern

490-770: A refrigerated tank near the freezing point of water with higher voltages than the thinner coatings. Hard anodizing can be made between 13 and 150 μm (0.0005" to 0.006") thick. Anodizing thickness increases wear resistance, corrosion resistance, ability to retain lubricants and PTFE coatings, and electrical and thermal insulation. Sealing Type III will improve corrosion resistance at the cost of reducing abrasion resistance. Sealing will reduce this greatly. Standards for thin (Soft/Standard) sulfuric anodizing are given by MIL-A-8625 Types II and IIB, AMS 2471 (undyed), and AMS 2472 (dyed), BS EN ISO 12373/1 (decorative), BS 3987 (Architectural). Standards for thick sulphuric anodizing are given by MIL-A-8625 Type III, AMS 2469, BS ISO 10074, BS EN 2536 and

560-436: A significant advantage when it comes to ruggedness or physical wear resistance. The reason for combining the processes can vary, however, the significant difference between anodizing and chromate conversion coating is the electrical conductivity of the films produced. Although both stable compounds, chromate conversion coating has a greatly increased electrical conductivity. Applications where this may be useful are varied, however

630-407: A thickness in the range of 30 nanometers (1.2 × 10  in) to several micrometers. Standards for titanium anodizing are given by AMS 2487 and AMS 2488. AMS 2488 Type III anodizing of titanium generates an array of different colours without dyes, for which it is sometimes used in art, costume jewellery , body piercing jewellery and wedding rings . The colour formed is dependent on the thickness of

700-409: A unique type of surface staining that can affect the structural integrity of the metal. Anodizing is one of the more environmentally friendly metal finishing processes. Except for organic (aka integral colour) anodizing, the by-products contain only small amounts of heavy metals , halogens , or volatile organic compounds . Integral color anodizing produces no VOCs, heavy metals, or halogens as all of

770-408: Is 2050°C (2323K), much higher than pure aluminium's 658°C (931K). This and the insulativity of aluminium oxide can make welding more difficult. In typical commercial aluminium anodizing processes, the aluminium oxide is grown down into the surface and out from the surface by equal amounts. Therefore, anodizing will increase the part dimensions on each surface by half the oxide thickness. For example,

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840-615: Is a statutory officer ( 10 U.S.C.   § 8013 ) and the head ( chief executive officer ) of the Department of the Navy , a military department within the United States Department of Defense . By law, the secretary of the Navy must be a civilian at least five years removed from active military service. The secretary is appointed by the president and requires confirmation by the Senate . The secretary of

910-421: Is also used to prevent galling of threaded components and to make dielectric films for electrolytic capacitors . Anodic films are most commonly applied to protect aluminium alloys , although processes also exist for titanium , zinc , magnesium , niobium , zirconium , hafnium , and tantalum . Iron or carbon steel metal exfoliates when oxidized under neutral or alkaline micro-electrolytic conditions; i.e.,

980-605: Is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called anodizing because the part to be treated forms the anode electrode of an electrolytic cell . Anodizing increases resistance to corrosion and wear, and provides better adhesion for paint primers and glues than bare metal does. Anodic films can also be used for several cosmetic effects, either with thick porous coatings that can absorb dyes or with thin transparent coatings that add reflected light wave interference effects. Anodizing

1050-504: Is anodized primarily as a primer for paint. A thin (5 μm) film is sufficient for this. Thicker coatings of 25 μm and up can provide mild corrosion resistance when sealed with oil, wax, or sodium silicate . Standards for magnesium anodizing are given in AMS 2466, AMS 2478, AMS 2479, and ASTM B893. Niobium anodizes in a similar fashion to titanium with a range of attractive colors being formed by interference at different film thicknesses. Again

1120-485: Is chromic acid anodizing, Type II is sulphuric acid anodizing, and Type III is sulphuric acid hard anodizing. Other anodizing specifications include more MIL-SPECs (e.g., MIL-A-63576), aerospace industry specs by organizations such as SAE , ASTM , and ISO (e.g., AMS 2469, AMS 2470, AMS 2471, AMS 2472, AMS 2482, ASTM B580, ASTM D3933, ISO 10074, and BS 5599), and corporation-specific specs (such as those of Boeing, Lockheed Martin, Airbus and other large contractors). AMS 2468

1190-436: Is obsolete. None of these specifications define a detailed process or chemistry, but rather a set of tests and quality assurance measures which the anodized product must meet. BS 1615 guides the selection of alloys for anodizing. For British defense work, a detailed chromic and sulfuric anodizing processes are described by DEF STAN 03-24/3 and DEF STAN 03-25/3 respectively. The oldest anodizing process uses chromic acid . It

1260-494: Is produced by auto-passivation. These pores allow for the dye to be absorbed, however, this must be followed by sealing or the dye will not stay. Dye is typically followed up by a clean nickel acetate seal. Because the dye is only superficial, the underlying oxide may continue to provide corrosion protection even if minor wear and scratches break through the dyed layer. Conditions such as electrolyte concentration, acidity, solution temperature, and current must be controlled to allow

1330-592: Is responsible for the formulation and implementation of policies and programs that are consistent with the national security policies and objectives established by the president or the secretary of defense. The secretary of the Navy is a member of the Defense Acquisition Board (DAB), chaired by the Under Secretary of Defense for Acquisition, Technology and Logistics . Furthermore, the secretary has several statutory responsibilities under

1400-424: Is sensitive to variations in the metallurgy of the underlying alloy and cannot be reproduced consistently. Anodizing in some organic acids, for example malic acid , can enter a 'runaway' situation, in which the current drives the acid to attack the aluminium far more aggressively than normal, resulting in huge pits and scarring. Also, if the current or voltage are driven too high, 'burning' can set in; in this case,

1470-459: Is the "lightfastness" of organic dyestuffs—some colours (reds and blues) are particularly prone to fading. Black dyes and gold produced by inorganic means ( ferric ammonium oxalate ) are more lightfast . Dyed anodizing is usually sealed to reduce or eliminate dye bleed out. White color cannot be applied due to the larger molecule size than the pore size of the oxide layer. Alternatively, metal (usually tin ) can be electrolytically deposited in

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1540-412: Is typically used to remove smut (residue), but is being replaced because of environmental concerns. The anodized aluminium layer is created by passing a direct current through an electrolytic solution, with the aluminium object serving as the anode (the positive electrode in an electrolytic cell). The current releases hydrogen at the cathode (the negative electrode) and oxygen at the surface of

1610-413: Is usually performed in an acidic solution, typically sulphuric acid or chromic acid, which slowly dissolves the aluminium oxide. The acid action is balanced with the oxidation rate to form a coating with nanopores, 10–150 nm in diameter. These pores are what allow the electrolyte solution and current to reach the aluminium substrate and continue growing the coating to greater thickness beyond what

1680-838: Is widely known as the Bengough-Stuart process but, due to the safety regulations regarding air quality control, is not preferred by vendors when the additive material associated with type II doesn't break tolerances. In North America, it is known as Type I because it is so designated by the MIL-A-8625 standard, but it is also covered by AMS 2470 and MIL-A-8625 Type IB. In the UK it is normally specified as Def Stan 03/24 and used in areas that are prone to come into contact with propellants etc. There are also Boeing and Airbus standards. Chromic acid produces thinner, 0.5 μm to 18 μm (0.00002" to 0.0007") more opaque films that are softer, ductile, and to

1750-739: The Medal of Honor and the Navy Distinguished Service Medal . On 7 August 1942, Congress revised the order of precedence, placing the Navy Cross above the Distinguished Service Medal in precedence. Since that time, the Navy Cross has been worn after the Medal of Honor and before all other awards. Additional awards of the Navy Cross are denoted by gold or silver 5 ⁄ 16 inch stars affixed to

1820-435: The Medal of Honor . The action must take place under one of three circumstances: The act(s) to be commended must be performed in the presence of great danger, or at great personal risk, and must be performed in such a manner as to render the individual's action(s) highly conspicuous among others of equal grade, rate, experience, or position of responsibility. An accumulation of minor acts of heroism does not justify an award of

1890-593: The Secretariat in a DoN setting, is the immediate headquarters staff that supports the secretary in discharging his duties. The principal officials of the Secretariat include the under secretary of the Navy (the secretary's principal civilian deputy), the assistant secretaries of the Navy (ASN), the general counsel of the Navy , the judge advocate general of the Navy (JAG), the Naval inspector general (NIG),

1960-539: The Uniform Code of Military Justice (UCMJ) with respect to the administration of the military justice system for the Navy & the Marine Corps, including the authority to convene general courts-martial and to commute sentences. The principal military advisers to the SECNAV are the two service chiefs of the naval services: for matters regarding the Navy the chief of naval operations (CNO), and for matters regarding

2030-780: The United States Coast Guard operates as a service within the Department of the Navy, the secretary of the Navy has the same powers and duties with respect to the Coast Guard as the secretary of homeland security when the Coast Guard is not operating as a service in the Department of the Navy. The Office of the Secretary of the Navy , also known within DoD as the Navy Secretariat or simply just as

2100-551: The United States Navy and the United States Marine Corps . The secretary of the Navy is responsible for, and has statutory authority ( 10 U.S.C.   § 8013 ) to "conduct all the affairs of the Department of the Navy", i.e. as its chief executive officer, subject to the limits of the law, and the directions of the president and the secretary of defense. In effect, all authority within

2170-526: The chief of Legislative Affairs , and the chief of naval research . The Office of the Secretary of the Navy has sole responsibility within the Department of the Navy for acquisition, auditing, financial and information management, legislative affairs, and public affairs. Pursuant to SecNavInst 5090.5F, the Department of the Navy Environmental Programs Manual , the secretary of the Navy and chief of naval operations recognize

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2240-657: The iron oxide (actually ferric hydroxide or hydrated iron oxide , also known as rust ) forms by anoxic anodic pits and large cathodic surface, these pits concentrate anions such as sulfate and chloride accelerating the underlying metal to corrosion. Carbon flakes or nodules in iron or steel with high carbon content ( high-carbon steel , cast iron ) may cause an electrolytic potential and interfere with coating or plating. Ferrous metals are commonly anodized electrolytically in nitric acid or by treatment with red fuming nitric acid to form hard black Iron(II,III) oxide . This oxide remains conformal even when plated on wiring and

2310-407: The 1960s. Thicknesses of up to 50 μm can be achieved. Organic acid anodizing is called Type IC by MIL-A-8625. Anodizing can be carried out in phosphoric acid, usually as a surface preparation for adhesives. This is described in standard ASTM D3933. Anodizing can also be performed in borate or tartrate baths in which aluminium oxide is insoluble. In these processes, the coating growth stops when

2380-483: The Department of the Navy to the Department of the Navy and Marine Corps, which would have also renamed the secretary of the Navy to the secretary of the Navy and Marine Corps , were introduced with wide support in the United States Congress , but failed due to the opposition of Senator and retired U.S. Navy officer John McCain . The Department of the Navy (DoN) consists of two uniformed services :

2450-460: The Marine Corps the commandant of the Marine Corps (CMC). The CNO and the Commandant act as the principal executive agents of the SECNAV within their respective services to implement the orders of the secretary. The United States Navy Regulations is the principal regulatory document of the Department of the Navy, and all changes to it must be approved by the secretary of the Navy. Whenever

2520-412: The Navy Cross. As originally authorized, the Navy Cross could be awarded for distinguished non-combat acts, but legislation of 7 August 1942 limited the award to acts of combat heroism. Past Navy Cross awards for merit, such as to 9th Chief of Naval Operations Fleet Admiral Ernest King , were unaffected by the change in criteria. The Navy Cross originally was the Navy's third-highest decoration, after

2590-428: The Navy and Marine Corps, unless specifically exempted by law, is derivative of the authority vested in the secretary of the Navy. Specifically enumerated responsibilities of the SECNAV in the aforementioned section are: recruiting, organizing, supplying, equipping, training, mobilizing, and demobilizing. The secretary also oversees the construction, outfitting, and repair of naval ships, equipment, and facilities. SECNAV

2660-523: The Navy was, from its creation in 1798, a member of the president's Cabinet until 1949, when the secretary of the Navy (and the secretaries of the Army and Air Force ) were by amendments to the National Security Act of 1947 made subordinate to the secretary of defense . On August 7, 2021, Carlos Del Toro was confirmed as secretary of the Navy. From 2001 to 2019, proposals to rename

2730-468: The ability to retain dye. Although anodizing only has moderate wear resistance, the deeper pores can better retain a lubricating film than a smooth surface would. Anodized coatings have a much lower thermal conductivity and coefficient of linear expansion than aluminium. As a result, the coating will crack from thermal stress if exposed to temperatures above 80 °C (353 K). The coating can crack, but it will not peel. The melting point of aluminium oxide

2800-544: The aluminium anode, creating a build-up of aluminium oxide. Alternating current and pulsed current is also possible but rarely used. The voltage required by various solutions may range from 1 to 300 V DC, although most fall in the range of 15 to 21 V. Higher voltages are typically required for thicker coatings formed in sulfuric and organic acid. The anodizing current varies with the area of aluminium being anodized and typically ranges from 30 to 300 A / m . Aluminium anodizing (eloxal or El ectrolytic Ox idation of Al uminium)

2870-425: The base metal converted. This will generally not be of consequence except where there are tight tolerances. If so, the thickness of the anodizing layer has to be taken into account when choosing the machining dimension. A general practice on engineering drawing is to specify that "dimensions apply after all surface finishes". This will force the machine shop to take into account the anodization thickness when performing

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2940-424: The byproducts found in the effluent streams of other processes come from their dyes or plating materials. The most common anodizing effluents, aluminium hydroxide and aluminium sulfate , are recycled for the manufacturing of alum, baking powder, cosmetics, newsprint and fertilizer or used by industrial wastewater treatment systems. Anodizing will raise the surface since the oxide created occupies more space than

3010-532: The chromate coating must remain intact. Beyond that, the chromate coating is then dissolved in unmasked areas. The component can then be anodized, with anodizing taking to the unmasked areas. The exact process will vary dependent on service provider, component geometry and required outcome. It helps to protect aluminium article. The most widely used anodizing specification in the US is a U.S. military spec , MIL-A-8625, which defines three types of aluminium anodizing. Type I

3080-547: The coating is susceptible to chemical dissolution in the presence of high- and low- pH chemistry, which results in stripping the coating and corrosion of the substrate. To combat this, various techniques have been developed either to reduce the number of fissures, to insert more chemically stable compounds into the oxide, or both. For instance, sulphuric-anodized articles are normally sealed, either through hydro-thermal sealing or precipitating sealing, to reduce porosity and interstitial pathways that allow corrosive ion exchange between

3150-497: The custom of decorating heroes from other nations, but the Medal of Honor was the sole U.S. award for valor at the time. The Army instituted the Distinguished Service Cross and Distinguished Service Medal in 1918, while the Navy followed suit in 1919, retroactive to 6 April 1917. Originally, the Navy Cross was lower in precedence than the Medal of Honor and the Navy Distinguished Service Medal , because it

3220-567: The dark color due to over- anodized finish. The medal is similar in appearance to the British Distinguished Service Cross . The service ribbon is navy blue with a center stripe of white identical to the suspension ribbon of the medal. The blue alludes to naval service; the white represents the purity of selflessness. United States Secretary of the Navy The secretary of the Navy ( SECNAV )

3290-464: The end. There are four laurel leaves with berries in each of the re-entrant arms of the cross. In the center of the cross, a sailing vessel is depicted on waves, sailing to the viewer's left. The vessel is a symbolic caravel of the type used between 1480 and 1500. Fraser selected the caravel because it was a symbol often used by the Naval Academy and because it represented both naval service and

3360-485: The film thickness is dependent on the anodizing voltage. Uses include jewelry and commemorative coins . Tantalum anodizes similarly to titanium and niobium with a range of attractive colours being formed by interference at different film thicknesses. Again the film thickness is dependent on the anodizing voltage and typically ranges from 18 to 23 Angstroms per volt depending on electrolyte and temperature. Uses include tantalum capacitors . An anodized oxide layer has

3430-416: The final machining of the mechanical part before anodization. Also in the case of small holes threaded to accept screws , anodizing may cause the screws to bind, thus the threaded holes may need to be chased with a tap to restore the original dimensions. Alternatively, special oversize taps may be used to precompensate for this growth. In the case of unthreaded holes that accept fixed-diameter pins or rods,

3500-606: The first sulfuric acid anodizing process was patented by Gower and O'Brien in 1927. Sulfuric acid soon became and remains the most common anodizing electrolyte. Oxalic acid anodizing was first patented in Japan in 1923 and later widely used in Germany, particularly for architectural applications. Anodized aluminium extrusion was a popular architectural material in the 1960s and 1970s, but has since been displaced by cheaper plastics and powder coating . The phosphoric acid processes are

3570-459: The formation of a consistent oxide layer. Harder, thicker films tend to be produced by more concentrated solutions at lower temperatures with higher voltages and currents. The film thickness can range from under 0.5 micrometres for bright decorative work up to 150 micrometres for architectural applications. Anodizing can be performed in combination with chromate conversion coating . Each process provides corrosion resistance, with anodizing offering

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3640-416: The interference between light reflected from the water-oil interface and the oil film's surface. Because the oil film's thickness isn't regulated, the resulting rainbow color appears random. In the anodizing coloring of aluminum, desired colors are achieved by depositing a controllably thick metal layer (typically tin) at the base of the porous structure. This involves reflections on the aluminum substrate and

3710-399: The issue of grounding components as part of a larger system is an obvious one. The dual finishing process uses the best each process has to offer, anodizing with its hard wear resistance and chromate conversion coating with its electrical conductivity. The process steps can typically involve chromate conversion coating the entire component, followed by a masking of the surface in areas where

3780-553: The most recent major development, so far only used as pretreatments for adhesives or organic paints. A wide variety of proprietary and increasingly complex variations of all these anodizing processes continue to be developed by industry, so the growing trend in military and industrial standards is to classify by coating properties rather than by process chemistry. Aluminium alloys are anodized to increase corrosion resistance and to allow dyeing (colouring), improved lubrication , or improved adhesion . However, anodizing does not increase

3850-478: The name of the recipient held in secret. One of those secret awardings was due to Marine Gunnery Sergeant Tate Jolly's actions during the 2012 Benghazi attack . The Navy Cross may be awarded to any member of the U.S. Armed Forces while serving with the Navy, Marine Corps, or Coast Guard (when a part of the Department of the Navy) who distinguishes themselves in action by extraordinary heroism not justifying an award of

3920-432: The obsolete AMS 2468 and DEF STAN 03-26/1. Anodizing can produce yellowish integral colours without dyes if it is carried out in weak acids with high voltages, high current densities, and strong refrigeration. Shades of colour are restricted to a range which includes pale yellow, gold, deep bronze, brown, grey, and black. Some advanced variations can produce a white coating with 80% reflectivity. The shade of colour produced

3990-1060: The oxide (which is determined by the anodizing voltage); it is caused by the interference of light reflecting off the oxide surface with light travelling through it and reflecting off the underlying metal surface. AMS 2488 Type II anodizing produces a thicker matte grey finish with higher wear resistance. Zinc is rarely anodized, but a process was developed by the International Lead Zinc Research Organization and covered by MIL-A-81801. A solution of ammonium phosphate , chromate and fluoride with voltages of up to 200 V can produce olive green coatings up to 80 μm thick. The coatings are hard and corrosion resistant. Zinc or galvanized steel can be anodized using DC at lower voltages (20–30 V) in silicate baths containing varying concentrations of sodium silicate , sodium hydroxide , borax , sodium nitrite , and nickel sulphate . The most common anodizing processes, for example, sulphuric acid on aluminium, produce

4060-547: The part is fully covered, and the thickness is linearly related to the voltage applied. These coatings are free of pores, relative to the sulfuric and chromic acid processes. This type of coating is widely used to make electrolytic capacitors because the thin aluminium films (typically less than 0.5 μm) would risk being pierced by acidic processes. Plasma electrolytic oxidation is a similar process, but where higher voltages are applied. This causes sparks to occur and results in more crystalline/ceramic type coatings. Magnesium

4130-414: The pores of the anodic coating to provide more lightfast colours. Metal dye colors range from pale champagne to black . Bronze shades are commonly used for architectural metals . Alternatively, the colour may be produced integral to the film. This is done during the anodizing process using organic acids mixed with the sulfuric electrolyte and a pulsed current. Splash effects are created by dying

4200-500: The strength of the aluminium object. The anodic layer is insulative . When exposed to air at room temperature, or any other gas containing oxygen, pure aluminium self-passivates by forming a surface layer of amorphous aluminium oxide 2 to 3 nm thick, which provides very effective protection against corrosion. Aluminium alloys typically form a thicker oxide layer, 5–15 nm thick, but tend to be more susceptible to corrosion. Aluminium alloy parts are anodized to greatly increase

4270-436: The supplies act as if nearly shorted and large, uneven and amorphous black regions develop. Integral colour anodizing is generally done with organic acids, but the same effect has been produced in laboratories with very dilute sulfuric acid. Integral colour anodizing was originally performed with oxalic acid , but sulfonated aromatic compounds containing oxygen, particularly sulfosalicylic acid , have been more common since

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4340-712: The surface and the substrate. Precipitating seals enhance chemical stability but are less effective in eliminating ionic exchange pathways. Most recently, new techniques to partially convert the amorphous oxide coating into more stable micro-crystalline compounds have been developed that have shown significant improvement based on shorter bond lengths. Some aluminium aircraft parts, architectural materials, and consumer products are anodized. Anodized aluminium can be found on MP3 players , smartphones , multi-tools , flashlights , cookware , cameras , sporting goods , firearms , window frames , roofs , in electrolytic capacitors, and on many other products both for corrosion resistance and

4410-418: The suspension and service ribbon of the medal. A gold star would be issued for each of the second through fifth awards, to be replaced by a silver star which would indicate a sixth award. To date no one has received more than five awards. Obverse: The medal is a modified cross pattée one and a half inches wide. The ends of its arms are rounded whereas a conventional cross patée has arms that are straight on

4480-416: The thickness of this layer for corrosion resistance. The corrosion resistance of aluminium alloys is significantly decreased by certain alloying elements or impurities: copper , iron , and silicon , so 2000-, 4000-, 6000 and 7000-series Al alloys tend to be most susceptible. Although anodizing produces a very regular and uniform coating, microscopic fissures in the coating can lead to corrosion. Further,

4550-458: The tradition of the sea. The laurel leaves with berries refer to achievement. Reverse: In the center of the medal, a bronze cross pattée, one and a half inches wide, are crossed anchors from the pre-1850 period, with cables attached. The letters USN are evident amid the anchors. The earliest version of the Navy Cross (1919–1928) featured a more narrow strip of white, while the so-called "Black Widow" medals awarded from 1941 to 1942 were notable for

4620-401: The unsealed porous surface in lighter colours and then splashing darker colour dyes onto the surface. Aqueous and solvent-based dye mixtures may also be alternately applied since the coloured dyes will resist each other and leave spotted effects. Another interesting coloring method is anodizing interference coloring. The thin oil film resting on the water's surface displays a rainbow hue due to

4690-403: The upper metal surface. The color resulting from interference shifts from blue, green, and yellow to red as the deposited metal layer thickens. Beyond a specific thickness, the optical interference vanishes, and the color turns bronze. Interference-colored anodized aluminum parts exhibit a distinctive quality: their color varies when viewed from different angles. The interference coloring involves

4760-705: The wiring is bent. Anodizing changes the microscopic texture of the surface and the crystal structure of the metal near the surface. Thick coatings are normally porous, so a sealing process is often needed to achieve corrosion resistance . Anodized aluminium surfaces, for example, are harder than aluminium but have low to moderate wear resistance that can be improved with increasing thickness or by applying suitable sealing substances. Anodic films are generally much stronger and more adherent than most types of paint and metal plating, but also more brittle. This makes them less likely to crack and peel from ageing and wear, but more susceptible to cracking from thermal stress. Anodizing

4830-438: Was awarded for both combat heroism and for "other distinguished service." Congress revised this on 7 August 1942, making the Navy Cross a combat-only decoration that follows the Medal of Honor in order of precedence. Since the medal was established, it has been awarded more than 6,300 times. It was designed by James Earle Fraser . Since the 11 September 2001 attacks the Navy Cross has been awarded 47 times, with two of them having

4900-526: Was first used on an industrial scale in 1923 to protect Duralumin seaplane parts from corrosion. This early chromic acid –based process was called the Bengough–Stuart process and was documented in British defence specification DEF STAN 03-24/3. It is still used today despite its legacy requirements for a complicated voltage cycle now known to be unnecessary. Variations of this process soon evolved, and

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