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ASTM B733-97 PDF

ASTM B Standard Specification for Autocatalytic (Electroless) Nickel- Phosphorus Coatings on Metal. This specification covers requirements for. A S T M BENGL W Ob T A U 4Tb – m AMERICAN origioauy published as B direct responsibility of Subcommittee B Advanced Plating Technologies, a Milwaukee, Wisconsin company, provides electroless nickel plating per MIL-C, ASTM B and AMS as well as.

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B — 97 Standard Specication for Autocatalytic Electroless Nickel-Phosphorus Coatings on Metal 1 This standard is issued under the xed designation B ; the number immediately following the designation indicates the aastm of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript epsilon e indicates an editorial change since the last revision or reapproval. This standard has been approved for use by agencies of the Department of Defense.

Because the deposited nickel alloy is a catalyst for the reaction, the process is self-sustaining. The chemical and physical properties of the deposit vary primarily with its phosphorus content and subsequent heat treatment. The chemical makeup of the plating solution and the use of the solution can affect the porosity and corrosion resistance of the deposit.

They are also used for the salvage of worn or mismachined parts. These coatings are used in applications requiring abrasion and wear resistance. These coatings are used in electronic applications providing solderability, bondability, increased electrical conductivity, and resistance to strong alkali solutions.

They are used on beryllium awtm titanium parts for low stress properties. Coatings with phosphorus contents greater than This standard does not purport to address all of the safety concerns, if any, associated with its use.

It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. Current edition approved July 10, Originally published as B — Last previous edition B — satm NOTE 1—Due to the precision of some phosphorus analysis methods a deviation of 0.

Rounding of the test results due to the precision of the limits provides for an effective limit of 4. For example, coating with a test result for phosphorus of 9. Typical environments include light-load lubricated wear, indoor corrosion protection to prevent rusting, and for soldering aastm mild abrasive wear.

It is characterized by industrial atmosphere exposure on steel substrates in dry or oiled environments.

Typical environments would include acid solutions, elevated temperature and pressure, hydrogen sulde and carbon dioxide oil service, high-temperature chloride systems, very severe wear, and marine immersion. NOTE 2—The performance of the autocatalytic nickel coating depends to a large extent on the surface nish of the article to be plated and how it was pretreated. Rough, non uniform surfaces require thicker coatings than smooth surfaces to achieve maximum corrosion resistance and minimum porosity.

NOTE 4—The purchaser should furnish separate test specimens or coupons of the basis metal for test purposes to be plated concurrently with the articles to be plated ashm 8. Materials and Manufacture 6.

Any such defects on signicant surfaces shall be brought to the attention of the purchaser before plating. The producer shall not be responsible for coatings defects resulting from surface conditions of the metal, if these conditions have been brought to the attention of the purchaser.

A suitable method astj activate the surface and remove oxide and foreign materials, which may cause poor adhesion and coating porosity. NOTE 5—Heat treatment of the base material may effect its metallurgical properties. An example is leaded steel which may exhibit liquid or solid embrittlement after heat treatment. Careful selection of the pre and post heat treatments are recommended.


Table 3 describes the heat treatment for maximum hardness. Avoid rapid heating and cooling of plated parts. Sufficient time must be allowed for large parts to reach oven temperature. NOTE 7—The length of time to reach maximum hardness varies with the phosphorus content of the deposit. High phosphorus deposits may require longer time or a higher temperature, or both.

Individual alloys should be tested for maximum hardness attainable, especially for conditions of lower temperatures and longer times. Do not use gas containing hydrogen with high-strength steel parts. The location of rack or wire marks in the coating shall be b733-7 upon between the producer and purchaser. The use of a statistical regimen asm establish the control limits and frequency of analysis may be employed to ensure quality deposits are produced.

Specication B may be consulted for a list of post treatments that are widely used. In all cases, the duration of the heat treatment shall commence from the time at which the whole of each part attains the specied temperature. Also, discoloration due to heat treatment shall not be cause for rejection unless special heat treatment atmosphere is specied see section 5. After coating and if specied, the part shall not exceed maximum dimension on signicant surface see section 5.

NOTE 9—The thickness of the coating cannot n733-97 controlled in blind or small diameter deep holes or where solution circulation is restricted. The test method, the duration of the test, and number of allowable spots per unit area shall be specied see section 5. The tests for these qualication requirements shall be performed monthly or more frequently. The weight percent of phosphorus shall be in the range designated by type classication see 4.

For Class 2 coatings, the microhardness shall equal or exceed a minimum of HK or equivalent Vickers see 4. The conversion of Vickers to Knoop using Tables E is not recommended. Properly performed this will ensure coated products of satisfactory quality and will reduce the amount of acceptance inspection. NOTE 10—Usually, when a collection of coated parts the inspection lot 8.

The inspection lot is then classied as complying or not complying with the requirements based on the results of the inspection sample. The size of the sample and the criteria of compliance are determined by the application of statistics. The procedure is known as sampling inspection. Three standards Test Method BGuide Band Test Method B contain sampling plans that are designed for the sampling inspection of coatings.

Test Method B contains four sampling plans, three for use with tests that are nondestructive and one for use with tests that are destructive. The purchaser and producer may agree on the plan s to be used. If they do not, Test Method B identies the plan to be used. Guide B provides a large number of plans and also gives guidance on the selection of a plan. When Guide B is specied, the purchaser and producer need to agree on the plan to be used.

Test Method B can be used only for coating requirements that have a numerical limit, such as coating thickness. The last must yield a numerical value and certain statistical requirements must be met.

Test Method B contains several plans and also gives instructions for calculating plans to meet special needs. An inspection lot shall be dened as a collection of coated parts which are of the same kind, that have been produced to the same specication, that have been coated by a single producer at one time or approximately the same time under essentially identical conditions, and that are submitted for acceptance or rejection as a group.


NOTE 11—The autocatalytic nickel process is dynamic and a daily sampling is recommended. For Asm requiring alloy analysis and corrosion testing weekly sampling should be considered as an option. NOTE 12—Inductively coupled plasma techniques can determine the alloy to within 0. The following analysis wavelength lines have been used with minimum interference to determine the alloy.

NOTE 13—Eddy-current type wstm give erratic measurements due to variations in conductivity of the coatings with changes in phosphorus content.

NOTE 14—To protect the edges, electroplate the specimens with a minimum of b373-97 m of nickel or copper prior to cross sectioning.

The instrument shall be calibrated with deposits plated in the same solution under the same conditions on magnetic steel. The instrument must be calibrated with standards having the same composition as the coating. Make sure that the surfaces measured are smooth, clean, and dry.

The surface of the coating shall be cleaned prior to testing see Note NOTE 16—This method is only recommended for deposits in the as-plated condition. The phosphorus content of the coating must be known to calculate the thickness of the deposit. Matrix effect due to the distribution of phosphorus in layers of the coating also effect the measurement accuracy and require that calibration standards be made under the same conditions as the production process.

When required, one of the following tests can be used on the plated part or specimen. After rinsing and air drying, examine the part for blue spots, which form at pore sites. Apply heat to the beaker at such a rate that the water begins to boil in not less than 15 min, nor more than 20 min after the initial application of heat.

Continue to boil the water for 30 min. Then remove the part, air dry, and examine for rust spots, which indicate pores. NOTE 19—Aerated water is prepared by bubbling clean compressed air through distilled water by means of a glass diffusion disk at room temperature for 12 h.

The pH of the aerated water should be 6. Fine cracks in the coating on the tension side of the bend are not an indication of poor adhesion.

ASTM B-733

Insertion of a sharp probe at the interface of the coating and basis metal to determine the adhesion is suggested. NOTE 17—Appropriate test specimens are strips approximately 25 to 50 mm wide, to mm long and 3 to 6 mm thick. Make three closely spaced indentations and examine under magnication for aking or blistering of the coating, which is cause for rejection.

The coating is examined b733-977 blistering or other evidence of poor adhesion at 43 magnication. It will vary depending on loads, type of indenter, and operator.

A g load is recommended. The rhombic Knoop indenter gives higher hardness readings than the square-base pyramidal Vickers diamond indenter for to g loads, see Ref 6. For maximum accuracy, a minimum coating thickness of 75 m is recommended.

ASTM B Specification | Electroless Nickel – Phosphorous Coatings | General Metal Finishing

Conversions of Vickers or Knoop hardness number to Rockwell C is not recommended. After 3 min contact, rinse, and apply a solution of alizarin sulfonate prepared by dissolving 1.

After 4 min contact, apply glacial acetic acid until the violet color disappears.