Back to results
US 5,178,916 AGranted
Process for making corrosion-resistant articles
AssigneeAT&T Bell Laboratories
InventorsChristopher E. D. Chidsey, Henry H. Law
Life of this patent
Estimating the term…
Abstract
Transition-metal-coated metallic elements, such as electrical contacts, are protected from corrosion by a novel surface treatment. In one embodiment, the treatment involves application of a phosphonate solution, optionally preceded by application of a chromatic solution phosphonate.
Claims17
A method for manufacturing a first plurality of metal-coated articles, wherein:
- each of said articles has a chemically modified external surface and a contact resistance associated with the external surface;
- associated with the coatings is a resistance to corrosion defined as the expected fraction of articles exhibiting contact resistances below a predetermined threshold after being subjected to a predetermined aging process;
- the method comprises the steps of:
- a) providing a first plurality of metal workpieces, each workpiece comprising a metal substrate and, formed on the substrate, a metal coating which has an external surface, wherein the metal coating comprises a transition metal selected from the group consisting of nickel, cobalt, titanium, chromium, and iron;
- and
- b) exposing each of said coating external surfaces to a liquid solution of a chemical compound selected from the group consisting of those phosphonic acids, and the salts thereof, which include at least 6 carbon atoms, resulting in a chemically modified coating external surface;
- and
- the exposing step is carried out such that:
- i) each of said modified surfaces has a contact resistance of about 50 m.OMEGA. or less;
- and ii) the resistance of the first plurality of articles to corrosion is increased, as compared to a second plurality of articles nominally identical to the first plurality but not exposed to such a liquid solution.
7 more elements
A method for manufacturing a first plurality of metal-coated articles, wherein:
- each of said articles has a chemically modified external surface and a contact resistance associated with the external surface;
- associated with the coatings is a resistance to corrosion defined as the expected fraction of articles exhibiting contact resistances below a predetermined threshold after being subjected to a predetermined aging process;
- the method comprises the steps of:
- a) providing a first plurality of metal workpieces, each workpiece comprising a metal substrate and, formed on the substrate, a metal coating which has an external surface, wherein the metal coating comprises nickel or a nickel alloy;
- b) exposing each of said coating external surfaces to a chromate solution;
- and
- c) then exposing each of said coating external surfaces to a liquid solution of a partially fluorinated alkyl phosphonic acid which includes at least about 6, but not more than about 14, perfluorinated carbon atoms, resulting in a chemically modified coating external surface;
- and
- the exposing steps are carried out such that:
- i) each of said modified surfaces has a contact resistance of about 50 m.OMEGA. or less;
- and ii) the resistance of the first plurality of articles to corrosion is increased, as compared to a second plurality of articles nominally identical to the first plurality but not exposed to such a liquid solution.
8 more elements
A method for manufacturing a first plurality of metal-coated articles, wherein:
- each of said articles has a chemically modified external surface and a contact resistance associated with the external surface;
- associated with the coatings is a resistance to corrosion defined as the expected fraction of articles exhibiting contact resistances below a predetermined threshold after being subjected to a predetermined aging process;
- the method comprises the steps of:
- a) providing a first plurality of metal workpieces, each workpiece comprising a metal substrate and, formed on the substrate, a metal coating which has an external surface, wherein the metal coating comprises a transition metal selected from the group consisting of nickel, cobalt, titanium, chromium, and iron;
- and
- b) exposing each of said coating external surfaces to a liquid solution of a monoester of phosphoric acid or of a salt of such monoester, resulting in a chemically modified coating external surface;
- the monoester belongs to the group which consists of the phosphatidic acids having the general formula ##STR2## wherein n is an integer in the range 10-16;
- and the exposing step is carried out such that:
- i) each of said modified surfaces has a contact resistance of about 50 m.OMEGA. or less;
- and ii) the resistance of the first plurality of articles to corrosion is increased, as compared to a second plurality of articles nominally identical to the first plurality but not exposed to such a liquid solution.
7 more elements
A method for lubricating a surface of a body which comprises a transition metal, transition metal alloy, or aluminum-containing alloy, the method comprising the step of applying to the surface a liquid solution which comprises a chemical compound having the formula
- CF.sub.3 (CF.sub.2).sub.m (CH.sub.2).sub.n PO(OH).sub.2,
- wherein m equals 5, 7, 9, or 11, and n equals 0, 1, or 2.
Dependencies are inferred from the claim text.