Search Results for brighteners

Chemical brightening (bright dipping) and electrolytic brightening (electropolishing) are essentially selective-dissolution processes, in which the high points of a rough surface of aluminum are attacked more rapidly than the depressions, and the peaks and valleys are smoothed to produce a bright and beautiful finish. This article discusses the metallurgical factors, optical factors, and applications of the chemical and electrolytic brightening. It compares the chemical brightening and electrolytic brightening, and presents the advantages of the chemical and electrolytic brightening processes in terms of performance and economy. The article describes the phosphoric-nitric acid baths and phosphoric-sulfuric acid baths used for chemical brightening. Solution compositions and operating conditions for three commercial electropolishing processes, as well as for suitable post-treatments, are presented in a table.

Aluminum or aluminum alloy products have various types of finishes applied to their surfaces to enhance appearance or improve functional properties. This article discusses the procedures, considerations, and applications of various methods employed in the cleaning, finishing, and coating of aluminum. These include abrasive blast cleaning, barrel finishing, polishing, buffing, satin finishing, chemical cleaning, chemical brightening, electrolytic brightening, chemical etching, alkaline etching, acid etching, chemical conversion coating, electroplating, immersion plating, electroless plating, porcelain enameling, and shot peening.

This article discusses the procedures used for pickling nickel and nickel alloys. Nickel alloys can be divided into four groups: high-nickel alloys, nickel-copper alloys, nickel-chromium alloys, and nickel-iron-chromium alloys. Alloys within each composition group that has similar surface conditions are pickled in the same solutions using the same procedures. The article discusses three different surface conditions for pickling these nickel alloys: bright annealed white surface requiring removal of tarnish by flash pickling; bright annealed oxidized surface requiring removal of a layer of reduced oxide, sometimes followed by a flash pickle to brighten; and black or dark-colored surface requiring removal of adherent oxide film or scale. The article also reviews specialized pickling operations of nickel alloys and various cleaning and finishing operations, including grinding, polishing, buffing, brushing, and blasting.

Electrodeposits of cadmium are used to protect steel and cast iron against corrosion. This article provides an overview of the surface preparation of, and brighteners used in, cyanide baths. It focuses on the anode system, current density, deposition rates, and bath temperature of cadmium plating with attention to the materials of construction and equipment used. The article provides a description of the selection of plating method with examples, applications, and several postplating processes of cadmium plating.

Commercial zinc plating is accomplished by a number of distinctively different systems: cyanide baths, alkaline noncyanide baths, and acid chloride baths. This article focuses on the composition, advantages, disadvantages, operating parameters, and applications of each of the baths. It provides information on the control of thicknesses of zinc specified for service in various indoor and outdoor atmospheres and on the similarities between cadmium and zinc plating.

This article discusses the process considerations and deposit properties of nickel plating. It describes the Watts solution and the anode materials used. The article focuses on the nickel plating processes used for decorative, engineering, and electroforming purposes. It provides information on the quality control of nickel plating. It concludes with a review of the environmental, health, and safety considerations associated with nickel plating.

A tin deposit provides sacrificial protection to copper, nickel, and many other nonferrous metals and alloys. Tin also provides good protection to steel. Tin can be deposited from either alkaline or acid electrolytes. This article explains the compositions and operating conditions of these electrolytes.

Anodizing refers to conversion coating of the surface of aluminum and its alloys to porous aluminum oxide. This article provides the reasons for performing anodizing and discusses the three principal types of anodizing processes, namely, chromic acid process, sulfuric acid process, and hard anodic process. It describes the limitations imposed by variables, such as alloy composition, surface finish, prior processing, temper or heat treatment, and the use of inserts, on the anodizing processes. The article explains the causes and means adopted for correcting several specific problems in anodizing aluminum. It also discusses the process control techniques and equipment used for anodizing. The article reviews the sealing processes for anodic coatings and the method for coloring the coatings. It concludes with a discussion on the effects of anodic coatings on the surface and mechanical properties of aluminum and its alloys.

Gold electroplating was invented in 1840. During the first 100 years electrodeposited gold was used primarily for its aesthetic appeal as a decorative finish. This article provides a description of the gold plating process and the electrolytes used. It discusses the decorative and industrial applications of gold plating. The article reviews factors affecting the dragout of gold solution.

This article provides a detailed account of the various alkaline and acid plating baths used for electrolytic copper plating. Dilute cyanide and Rochelle cyanide baths, high-efficiency sodium and potassium cyanide baths, alkaline noncyanide copper plating baths, and alkaline copper pyrophosphate baths, are discussed. The article reviews acid plating baths such as copper sulfate bath and copper fluoborate bath. It also presents information on the surface preparation considerations, bath composition, and operating variables of copper plating as well as the equipment used.

Copper can be electrodeposited from numerous electrolytes. Cyanide and pyrophosphate alkalines, along with sulfate and fluoborate acid baths, are the primary electrolytes used in copper plating. This article provides information on the chemical composition, plating baths, and operating conditions of electrodeposition processes for chromium plating, nickel plating, iron plating, cadmium plating, zinc plating, indium plating, lead plating, tin plating, silver plating, gold plating, brass plating, bronze plating, tin-lead plating, zinc-iron plating, and zinc-nickel plating. The article also discusses selective plating, electroforming, and other processes and where they are typically used.

Nickel alloys electroplated for engineering applications include nickel-iron, nickel-cobalt, nickel-manganese, and zinc-nickel. This article provides the process description and discusses the processing variables, properties, advantages, and disadvantages of nickel-iron, nickel-cobalt, nickel-manganese alloys, and nickel chromium binary and ternary alloys. It also includes information on the environmental, health, and safety considerations for these nickel-base alloys.

Etching aluminum can be a pretreatment step for anodizing, chemical conversion coating, metal-to-rubber bonding, and a host of other processes. Chemical etching, using either alkaline or acid solutions, produces a matte finish on aluminum products. This article describes the alkaline etching and acid etching of aluminum. Alkaline etching reduces or eliminates surface scratches, nicks, extrusion die lines, and other imperfections. Acid etching can be done without heavy smut problems, particularly on aluminum die castings. Hydrochloric, hydrofluoric, nitric, phosphoric, chromic, and sulfuric acids are used in acid etching. The article presents a flow chart of the operations used in acid etching.

Pulsed-current plating can be defined simply as metal deposition by pulsed electrolysis, which involves using interrupted direct current to electroplate parts. This article discusses the advantages and limitations of pulsed-current plating and provides information on the process principles and control, solution composition, operating conditions, and necessary equipment modifications.

Electroplated silver is used in both decorative and functional applications, such as engineering and electrical/electronic applications. This article explains the solution formulations and specifications of electrolytes used in silver plating.

Copper alloys are widely used as electroplated coatings. They can also be used with practically any substrate material that is suitable for electroplating. This article focuses on the solution composition and operating conditions for brass and bronze plating solutions. It describes the decorative and engineering applications of brass and bronze plating. The article also provides information on the treatment of waste water from brass and bronze plating operations.