JPH04301062A - Base material having improved plasma flame spray coated surface type - Google Patents

Abstract

A metal surface is now described having enhanced adhesion of subsequently applied coatings. The substrate metal of the article, such as a valve metal as represented by titanium, is provided with a highly desirable surface characteristic for subsequent coating application. This can be achieved by a plasma sprayed coating of well defined surface morphology, the plasma spraying being with one or more metals usually valve metals. The metal of the coating may be the same or different from the metal of the substrate. Subsequently applied coatings, by penetrating into the coating of well defined surface morphology, and desirably locked onto the resulting metal article an provide enhanced lifetime even in rugged commercial environments.

Description

[Detailed description of the invention]

0001

FIELD OF INDUSTRIAL APPLICATION The present invention relates to metal products from substrates with metal-containing surfaces suitable for strengthening coating adhesion, plasma metal products for strengthening coating adhesion which are grooved and have therefore lost their planarity. The present invention relates to a method for preparing a surface and an electrolytic cell having an electrode of the metal product described above.

0002

BACKGROUND OF THE INVENTION The adhesion of coatings applied directly to substrate metal surfaces is particularly critical when the coated metal is used in harsh industrial environments. Usually, surface preparation and pretreatment operations before coating are carefully carried out. In such treatment or pretreatment operations, a clean surface is of paramount importance.

[0003] A typical example of a coating applied directly to the base metal is an electrocatalytic coating, which often contains a noble metal of the platinum group, and is applied directly onto a metal such as valve metal. In the art of electrocatalytic coatings applied to base metals, the metal is simply cleaned to a very smooth surface. US Patent No. 4
, 797, 182 specification. Fluorine compound treatment smoothes the surface. U.S. Pat. No. 3,864,163. Cleaning includes chemical degreasing, electrolytic degreasing, or treatment with oxidizing acids. U.S. Pat. No. 3,864,163. After cleaning, the surface for coating is prepared by mechanical roughening. U.S. Pat. No. 3,778,307. If the mechanical treatment is sandblasting, then etching is performed. U.S. Pat. No. 3,878,083. Alternatively, a fine mixture of metal powders may be applied subsequently by flame spraying. U.S. Pat. No. 4,849,085.

An alternative method for securing new coatings to the substrate is to form a layer of porous oxide on the base metal, which is useful in applying electrocatalytic coatings to valve metal. It was discovered that For example, U.S. Pat.
As disclosed in US Pat. No. 140,813, the active material can be applied electrochemically after flame spraying or plasma spraying titanium oxide onto the base metal. Alternatively, the thermal spray material pre-applied with electrocatalytically active particles may be a metal oxide, nitride, etc., as taught in US Pat. No. 4,392,927.

However, it is difficult to provide long-life coated metal products for the oxygen generating anodes currently used commercially in the most demanding commercial environments such as electroplating, electrotinning, electroforming or electrowinning. be. The operations described above are continuous operations and involve severe conditions including the possibility of surface damage. It would be most desirable if such an operation could provide a coated metal substrate as an electrode that can be stably operated over a long period of time while maintaining excellent bonding of the coating. It would also be highly desirable to be able to provide such electrodes not only from virgin metal, but also from recoated metal.

[0006]

[Problem to be Solved by the Invention] Locked on coating is now the predominant coating adhesion.
) was discovered. Metallic substrates thus coated can have highly desirable long lifetimes even in the harshest industrial environments. In electrocatalytic coatings, even when using gouged or similarly misshapen base metals, the present invention can provide well-fixed coatings with uniform planarity.

One aspect of the invention is a metal article from a substrate having a metal-containing surface suitable for enhancing coating adhesion, such surface being a valve metal that has been plasma sprayed onto said substrate. The plasma sprayed surface has an average surface roughness of greater than or equal to 250 microinches as measured by a profilometer and a profilometer upper threshold of 10.2 micrometers. (400 microinches) and an average of about 15.7 surface peaks per centimeter (40/inch) or more based on a profilometer lower threshold of 7.6 μm.

Another aspect of the invention is a method of preparing a plasma metal surface for coating adhesion enhancement on a surface that has been grooved and thus has lost planarity, the method comprising ), the valve metal is plasma sprayed to establish the flatness of the metal surface, and then the surface to be coated, including the plasma sprayed slots, is plasma sprayed to provide a surface roughness that enhances coating adhesion.

A still further aspect of the invention is an electrolytic cell having one or more electrodes of metal article as defined herein. When this metal product is coated with an electrocatalytic coating and used as an oxygen generating electrode, it can be used under harsh commercial operations including continuous electrogalvanizing, electrotinning, copper foil plating, electroforming or electrowinning and sodium sulfate electrolysis. Such electrodes can have a very desirable service life. The invention therefore also extends to metal products such as those used as electrodes.

0010

[Means for Solving the Problems] The base metal can be broadly understood as any metal that can be coated. For the specific application of electrocatalytic coatings, the base metal can be metals such as nickel or manganese, but is almost always titanium, tantalum,
Valve metals would include aluminum, zirconium and niobium. Titanium is of particular interest because of its roughness, corrosion resistance, and availability. Metals suitable as substrates include commonly available elemental metals, as well as alloys and intermetallic mixtures containing one or more valve metals, as well as ceramics and cermets. For example, titanium can be alloyed with nickel, cobalt, iron, manganese or copper. In more detail, grade 5 titanium is 6.7
Contains up to 5% aluminum and 4.5% vanadium, grade 6 titanium contains up to 6% aluminum and 3% tin, grade 7 titanium 0.25% by weight
Grade 10 titanium contains 10-13% molybdenum and 4.5-7.5% zirconium, and so on.

The use of elemental metals, alloys and intermetallic mixtures is specifically meant to use metals in normally available conditions, ie metals containing small amounts of impurities. That is, titanium, which is a metal of particular interest, is available in various grades, including other components that are alloys or alloys plus impurities. Titanium grades are described in more detail in ASTM B 265-79 Standard Specification for Titanium.

[0012] Regardless of the metal chosen and the subsequent treatment applied to the metal surface, it is advantageous for the surface of the base metal to be clean. This can be achieved with any process that cleans the metal surface, but in cases where removal of old coatings is not required or where etching is used.
Mechanical cleaning is typically minimized, as explained in more detail below. That is, conventional cleaning methods such as chemical or electrolytic degreasing or other chemical cleaning operations can be advantageously used.

If an old coating is present on the metal surface, it is necessary to check whether the above cleaning is necessary before recoating. To maximize performance when using finished products with electrocatalytic coatings such as for oxygen generating electrodes,
Preferably, the old coating is removed. The technical field of the invention relates to electrochemically active coatings on valve metals:
Chemical means of coating removal are well known. That is, when pickled immediately after treatment with a melt of essentially basic material, as taught in U.S. Pat. No. 3,573,100, the metal surface is suitably reconstituted. . Also,
Treatment with an alkali metal hydroxide melt containing an alkali metal hydride followed by treatment with a mineral acid is useful, as described in U.S. Pat. No. 3,706,600. Conventional rinsing and drying steps can also form part of these operations.

In the practice of the present invention, if the electrocatalytic coating is applied to the valve metal after the surface has been cleaned or after the surface has been prepared and cleaned, the surface will become rough. This is accomplished by plasma spray application, usually by means of finely divided valve metal, particularly titanium powder. However, as explained below, although the metal is applied in particulate form, the supplied or applied metal may be in another form, such as in the form of a wire. It should be understood that it is for convenience's sake that the coating method will be described using coating of fine metal particles as a representative example. In this plasma spraying process, metal is melted and an inert gas such as argon or nitrogen, optionally containing a small amount of hydrogen, is heated to high temperatures with an electric arc, and the molten metal is dispersed into the resulting plasma stream. be. The term "plasma spraying" as used in the present invention should generally be understood to include thermal spraying methods such as magnetohydrodynamic spraying, flame spraying and arc spraying, although plasma spraying is preferred. Must be.

Thermal spray parameters, such as the volume and temperature of the flame or plasma spray stream, the feed rate of the particulate metal component, etc., are such that the particulate metal component is thereby melted in the spray stream and in a substantially molten form. It is chosen to remain deposited on the base metal, thus resulting in an essentially continuous coating with a porous structure (ie, a coating in which the sprayed particles are indistinguishable). Typically, spray parameters such as those used in the Examples will provide satisfactory coverage. Normally, the base metal during melt spraying is maintained at a temperature close to room temperature. this is,
This can be accomplished by means such as directing an air stream onto the substrate during thermal spraying or cooling the substrate in air between thermal spraying passes.

[0016] The typical particle size range of the particulate metal used, such as titanium powder, is 20-100 microns, and it is preferred that all particles fall within the range of 40-80 microns to effectively roughen the surface. . Metal particles with different particle sizes are equally suitable as long as they are easily plasma sprayed. The composition of the particulate metal is similar to that described above for the base metal, eg, titanium is one of several grades, typically grade 1 titanium. It is also conceivable to apply mixtures, for example mixtures of metals or mixtures of metals and other components. Other components also include metal oxides. In a mixture of a metal and other components, for example, the metal accounts for the majority and the other ingredients account for the minor amount. It is also conceivable to use such plasma spray coating in combination with etching of the base metal surface. The respective treatments are almost always applied to different parts of the surface. When using etching, the metal surface is violently etched to bring out deep grain boundaries.
It is important to fully expose the three-dimensional grains. It is preferable that impurities near grain boundaries be etched by such an operation. Especially if there is an old covering,
If the coated substrate is used, for example, as an anode in electroplating, the metal article may lose its shape and lose its surface planarity. Typically, such distortions will be surface defects or slots. For convenience, surface distortions including chips, scratches, and slots, as well as burns where the metal actually melts and resolidifies, are all generally referred to herein as "gouges." These slots may or may not be filled with metal. If the entire surface is subsequently etched before recoating, it is expected that the etching effect of the filled areas may be poor. Additionally, the slots in the base material may be stretched, or the base material may be affected by thermal history and/or
Alternatively, the etching may not produce the desired result due to chemical action. Therefore, it is particularly desirable to simply plasma spray the entire surface so that these substrate defects can be overcome. In some cases, a combination of plasma spraying and etching may be useful. In other words, slots and holes are filled using plasma spraying technology. Typically, the uncorrupted surface area is etched first, and then this flat etched surface is masked.
The remaining slots are filled and/or surface treated by plasma spray application. That is, plasma spraying can be used to fill and reactivate the grooves, or it can be used to simply reactivate the grooves without necessarily restoring the planarity of the surface. . Reactivation refers to a plasma spray application that prepares the slots for subsequent treatment. In this way, the entire surface has the necessary roughness for the coating. If desired, it may be repolished to the desired flatness during this same process.

When using etching, the heat treatment history of the metal may be important. For example, in preparing a metal such as titanium for etching, it is most useful to condition the metal by annealing or the like to diffuse impurities into the grain boundaries. For example, properly annealing grade 1 titanium increases the concentration of iron impurities at the grain boundaries. When the preferred conditioning is annealing and the metal is grade 1 titanium, the titanium can be annealed at a temperature of about 500° C. or more for a time of about 15 minutes or more. From the point of view of operational efficiency, for example, 6
Higher annealing temperatures, such as 00-800°C, are advantageous.

If etching is used, it is carried out with a sufficiently active etching solution that aggressively attacks grain boundaries. Typical etching solutions are acidic solutions and can be hydrochloric, sulfuric, perchloric, sulfuric, oxalic, tartaric, and phosphoric acids, and mixtures thereof, such as aqua regia. Other etching agents that can be used include caustic etchants such as potassium hydroxide/hydrogen peroxide mixtures or melts of potassium hydroxide and potassium nitrate. From the point of view of operational efficiency, it is advantageous for the etching solution to be a strong or concentrated solution, such as a 18-22% by weight hydrochloric acid solution. Furthermore, when etching this solution, if it is an aqueous solution, the temperature is 80°C.
Advantageously, the temperature is maintained at elevated temperatures, such as at or near boiling conditions, or at higher temperatures, such as at reflux. After etching, the etched metal surface can be subjected to a rinsing and drying process to prepare the surface for coating. Further details regarding etching and annealing are provided in U.S. Patent Application No. 374;
No. 429, the disclosure of which is cited.

Regarding the surface roughness of plasma sprayed coatings, the metal surface has an average roughness (Ra) of greater than or equal to about 6.4 μm (250 microinches) and an average roughness of about 15.7 (40 particles per centimeter). /inch) or more. The number of surface peaks per centimeter is typically below the lower threshold of 7.6 μm.
(300 microinches) and upper threshold 10.2 μm
(400 microinches). A surface having an average roughness of less than about 6.2 μm (250 microinches) is undesirably smooth for the substantial enhancement of coating adhesion that is required and has an average roughness of less than about 15.7 particles per centimeter. The same applies to surfaces having surface peaks. greater than about 10.2 μm (400 microinches), such as about 19.1 to 38.1 μm (7
A surface having an average roughness in the range of 50-1500 microinches) and containing no low spots less than about 5.1 micrometers (200 microinches) is advantageous. Approximately 5.3 to 5.6 μm to successfully avoid surface smoothness
Advantageously, the surface does not contain low spots of less than (210-220 microinches). Surfaces having a surface roughness of about 300 to 500 microinches are preferred. Advantageously, the average number of peaks per centimeter of surface is greater than or equal to about 23.6 peaks (60 peaks/inch) and less than about 51.1 peaks per inch (60 peaks/inch).
130 pieces/inch) or more, but on average about 31 pieces/inch)
．． 4 to about 47.2 pieces/cm (80 to 12
0 pieces/inch) is preferable. The average distance (Rm) between the maximum peak and maximum trough is approximately 25.4 μm (10
00 microinches) and have an average peak height (Rz) of about 25.4 μm (1000 microinches). All of the above surface properties are measured using a profilometer. Rm value is about 38
．． 1 to 88.9 μm (1500 to 3500 microinches), with a maximum valley characteristic of approximately 38.1 to 88
．． A coating surface of 9 μm (1500 to 3500 microinches) is more desirable.

[0020] After the substrate has achieved the required surface roughness, the surface is subjected to various operations, including pretreatment, before being coated. For example, the surface is subjected to a cleaning operation such as solvent cleaning. Alternatively, it is subjected to subsequent etching, hydrogenation treatment, or nitridation treatment. Prior to coating with the electrochemically active material, an oxide layer is formed by heating the substrate in air or by anodic oxidation, as described in U.S. Pat. No. 3,234,110. It is proposed that the European Patent Application No. 0,090,425
The patent proposes electroplating the substrate with platinum, followed by chemical deposition of oxides of ruthenium, palladium or iridium thereon. Various proposals have also been made to deposit an outer layer of electrochemically active material on the underlying layer, which primarily serves as a protective and conductive intermediate. GB 1,344,540 discloses the use of an electrodeposited layer of cobalt or lead oxide under a ruthenium-titanium oxide or similar active outer layer. U.S. Patent No. 4,272,354, U.S. Patent No. 3,882,002
No. 3,950,240 discloses various tin oxide-based underlayers.

After imparting the necessary surface roughness and performing any pretreatment, the coating most contemplated by the present invention is an electrochemically active coating, typically made of platinum or other platinum group metals. They can be described as active oxide coatings, such as platinum group metal oxide, magnetite, ferrite, cobalt spinel or mixed metal oxide coatings. Such coatings are typically developed for anode coatings in the electrochemical industry. These are water-based or solvent-based, for example using alcoholic solvents. Preferred coatings of this type are described in U.S. Pat. Nos. 3,265,526 and 3,632.
, 498; 3,711,385; and 4,528,084. Mixed metal oxide coatings often include one or more valve metal oxides, including oxides of platinum group metals, including platinum, palladium, rhodium, iridium, and ruthenium, or mixtures thereof, as well as other metals. Further coatings in addition to those listed above include manganese dioxide, lead dioxide, platinates such as MxPt3O4 (M is an alkali metal and x is typically targeted at about 0.5). coating, nickel-nickel oxide and nickel
Plus there are lanthanide oxides.

It is contemplated that the coating may be applied to the metal by any means useful for applying liquid coating compositions to metal substrates. Such methods include dip spin and dip dry.
n) method, brush application method, roll coating method and spray application methods such as electrostatic spraying. Furthermore, it is also possible to use a combination technique with a spray application method, for example a combination of a dip and drain method and a spray application method. Regarding said coating compositions which provide electrochemically active coatings,
The dipping/draining modification method is the most useful. After any of the coating operations described above, the liquid coating composition is removed and the coated metal surface is immersed and drained or subjected to other treatments such as forced air drying.

Typical curing conditions for electrocatalytic coatings are curing temperatures of about 300 to about 600°C. Curing times vary for each coating layer and can vary from just a few minutes to over an hour. For example, if several coating layers are applied, the curing time will be longer. However, curing operations that overlap with annealing conditions at elevated temperatures and long-term exposure to such elevated temperatures are generally avoided for economic reasons. Generally, the curing technique used can be any that can be used to cure coatings on metal substrates. That is, oven curing, including conveyor ovens, can be used. Furthermore, infrared curing techniques can also be used. For the most economical curing, the use of oven curing is preferred, and the curing temperature used for electrocatalyst coatings ranges from about 450 to about 550°C.
within the range of ℃. At such temperatures, the curing time of each applied coating layer is almost always only a few minutes, for example 3 to 10 minutes. The following examples illustrate how the present invention was carried out and comparative examples. However, this example illustrating how the invention may be practiced should not be construed as limiting the invention.

[0024]

EXAMPLE 1 A titanium nut was welded to the back side of each sample plate having an approximately 7.5 cm2 sample surface made of unalloyed Grade 1 titanium. Next, this sample plate was placed on a large metal backing plate, and the sample plate was arranged in a mosaic pattern. This stacking arrangement functioned as a large array of sample plates that could be handled as a unit in the following operations. This sample plate was grit blasted with aluminum oxide, rinsed with acetone, and dried.

A titanium powder coating was formed on the sample plate using titanium powder with an average particle size of 50-60 microns. G.H.
A sample plate was coated with this powder using a Metco plasma spray gun equipped with a spray nozzle. Thermal spraying conditions were: current 500 amps; voltage 45-50 volts;
Plasma gas argon and helium; titanium feed rate 1-36 kg (3 lb)/hour; spray band width
and the spray distance was 64 mm, and the resulting thickness of the titanium layer on the titanium sample plate was approximately 150 microns.

The coated surface of the sample plate was then subjected to surface profilometer measurements using a Hommel model T1000 C instrument manufactured by Hommelwerk GmbH. Profilometer measurements of the sample plate surface were determined by calculating the average value from three separate measurements made with the instrument running in random orientations across the coated flat surface of the sample plate. As a result, the average values of surface roughness (Ra) measured for the three samples were 11.4 and 12.
4 and 13.9 μm (448, 490, and 548 microinches), and the peak numbers/cm (Nr) were 29.9, 24.8, and 29.9 (76
．． 63 and 76 pieces/inch). The number of peaks per centimeter was measured within threshold limits of 7.6 μm (300 microinches, lower limit) and 10.2 μm (400 microinches, upper limit).

[0027]

Example 2 A titanium sample previously coated with an electrochemically active coating was blasted with alumina powder to remove the previous coating. The removal of the previous coating by this polishing method was determined by X-ray fluorescence. After removing the polishing residue, the resulting sample plate was etched. It was etched away by immersion in a 20% by weight aqueous hydrochloric acid solution heated to 95° C. for about 1 hour. After removing the sample plate from the hot hydrochloric acid, it was rinsed again with deionized water and air dried. According to profilometer measurements performed using the method of Example 1, the average value on the flat surface of the sample was Ra 4.6 μm (18
0 microinch) and Nr 12.2 pieces/cm (31
pieces/inch).

The samples were then coated with plasma sprayed titanium using the titanium powder and coating method described in Example 1. According to profilometer measurements carried out according to the method of Example 1, the average value on the flat surface of the sample was Ra 16.5
μm (650 microinches) and Nr27.2 pieces/
cm (69 pieces/inch).

Claims (33)

[Claims] 1. A metal article from a substrate having a metal-containing surface suitable for enhancing coating adhesion, said surface being a valve metal surface that has been plasma sprayed onto said substrate, said plasma sprayed The applied surface has an average surface roughness of approximately 6.4 μm (250 microinches) or more as measured by a profilometer, and a profilometer upper limit threshold of 10.2 μm.
(400 microinches) and profilometer lower threshold of 7.6 μm (300 microinches),
Approximately 15.7 pieces per centimeter (40 pieces/inch)
A metal product characterized by having an average surface peak of or more than 100%. 2. The metal article of claim 1, wherein said substrate comprises a valve metal substrate of one or more of metals, alloys, intermetallic mixtures, ceramics, or cermets. 3. The metal article of claim 1, wherein the surface metal is selected from the group consisting of metals, alloys and intermetallic mixtures of titanium, tantalum, niobium, aluminum, zirconium, manganese and nickel. 4. The surface is a plasma sprayed surface obtained by applying valve metal particles having a particle size in the range of 20 to 100 microns.
metal products. 5. The metal article of claim 1, wherein said metal article is an oxygen generating anode. 6. The metal product according to claim 1, wherein said metal product is an electrode other than an oxygen generating anode. 7. The metal surface has an average roughness of at least about 7.6 μm (300 microinches) as measured by a profilometer, with a low spot of less than about 5.3 μm (210 microinches). The metal product according to claim 1, which does not contain. 8. The surface has an upper threshold of 10.2 μm.
(400 microinches) and lower threshold 7.6μm (3
2. The metal article of claim 1, having an average surface peak of greater than or equal to about 23.6 peaks per centimeter (60 peaks per inch) as measured by a profilometer based on 0.00 microinches. 9. The surface has a diameter of about 25.4 μm (1000 microinches) as measured by a profilometer.
The metal product according to claim 1, having a maximum peak-to-maximum trough average distance equal to or greater than or equal to the maximum average distance. 10. The metal article of claim 1, wherein said surface has an average maximum peak to maximum valley distance of about 1500 to 3500 microinches as measured by a profilometer. 11. The metal article of claim 1, wherein said surface has an average peak height of greater than about 1000 microinches as measured by a profilometer. 12. The metal article of claim 1, wherein said surface has an average height of about 1500 to 3500 microinches as measured by a profilometer. 13. The metal product of claim 1, wherein said surface is coated. 14. The metal article of claim 13, wherein said coated surface has an electrochemically active surface coating comprising a platinum group metal, metal oxide, or mixtures thereof. 15. The metal of claim 13, wherein said electrochemically active surface coating contains one or more oxides selected from the group consisting of platinum group metal oxides, magnetite, ferrite, and cobalt oxide spinel. product. 16. The metal article of claim 13, wherein said electrochemically active surface coating comprises a mixed crystalline material of one or more valve metal oxides and one or more platinum group metal oxides. 17. The coated surface comprises manganese dioxide, lead dioxide, particulate tin, platinate substitutes.
14. The metal article of claim 13, having a coating containing one or more of nickel-nickel oxide and nickel plus lanthanide oxide. 18. The metal product according to claim 1, wherein the metal product is an anode for an anodizing tank, an electroplating tank, or an electrowinning tank. 19. The metal product according to claim 1, wherein said metal product is an anode for electrolytic galvanizing, electrolytic tin plating, sodium sulfate electrolysis, or copper foil plating. 20. A method for flattening a metal surface that has lost its flatness due to grooves in order to strengthen coating adhesion, the method comprising:
a) plasma spraying a bulb metal into the slots in said surface to level the surface; and (b) plasma spraying the surface to be coated, including the plasma sprayed slots, to enhance coating adhesion. A method characterized by making the surface rough. 21. The slot is first partially filled with welding material and then the valve metal is plasma sprayed.
0 method. 22. The slot is first polished to provide a polished slot for plasma spray applied metal.
0 method. 23. A method for making the surface of a coated metal that has lost its flatness due to grooves during use into a flat surface for recoating, the method comprising: (a) melting the coated metal surface into a flat surface for recoating; (b) removing said coating by exposing it to a melt containing;
separating said metal surface from said melt, cooling said metal surface and removing melt residue therefrom; (c) intergranular etching of said surface using a strong acid or caustic etchant at elevated temperature; etching; (d) cleaning the etched surface exposing the slots; (e) plasma spraying a valve metal into the slots in the surface to planarize and roughen the metal surface; (f) such that said surface has a surface roughness for surface planarity and enhanced coating adhesion, and said surface roughness is established both by intergranular etching and by plasma spraying; A method characterized by: 24. The surface separated from the melt is annealed at an elevated temperature for a period sufficient to remove impurities on the surface of the intermediate metal into an at least substantially continuous intergranular network. 24. The method of claim 23. 25. Said slot is first partially filled with molten material and then plasma sprayed with valve metal.
Method 3. 26. The method of claim 23, wherein said slot is first polished to provide a polished slot for plasma spray applied metal. 27. A cell for electrolyzing dissolved chemical species contained within the bath, the cell having an anode immersed in the bath, the cell having an electrical conductor as an operating surface on a base metal. The anode has a chemically active surface coating, the base metal has a roughened surface of plasma sprayed valve metal, and the surface has a roughened surface of approximately 6.4 μm (as measured by a profilometer). Average surface roughness greater than 250 microinches and profilometer lower threshold of 7.6 microinches (30
0 microinch) and profilometer upper threshold 10
．． A battery case having an average surface peak of about 15.7 peaks per centimeter (40 peaks/inch) or more based on 2 μm (400 microinches). 28. The surface has an average roughness of at least about 7.6 μm (300 microinches) and a low spot of less than about 5.3 μm (210 microinches) as measured by a profilometer. 28. The battery case of claim 27. 29. The surface has an upper threshold of 10.2μ
m (400 microinches) and lower threshold 7.6 μm (
300 microinches), approximately 23.6 particles per centimeter (60 particles per centimeter).
28. The battery container of claim 27, having an average surface peak of at least 1 inch. 30. The battery case of claim 27, wherein said surface has an average maximum peak to maximum valley distance of greater than about 1000 microinches as measured by a profilometer. 31. The battery case of claim 27, wherein said surface has a maximum peak to maximum valley average distance of about 1500 to 3500 microinches as measured by a profilometer. . 32. The container of claim 27, wherein said surface has an average peak height of greater than about 1000 microinches as measured by a profilometer. 33. The surface has a diameter of about 38.1 to about 76.2 μm (1500 μm) as measured by a profilometer.
28. The battery case of claim 27, having an average peak height of from 3000 microinches to 3000 microinches.