Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
173 words
A method of producing a steel sheet plated with a Pb-Sn alloy, suitable for use as the material for automobile fuel tanks adapted to receive alcohol-containing fuel therein, said method comprising the steps of: (1) plating a steel sheet with Ni to a thickness of 0.01 to 1μ; (2) dipping said steel sheet in a plating bath of a Pb-Sn system alloy at 320° to 400° C. for 1 to 10 seconds to effect a hot dip plating; and then (3) cooling said steel sheet rapidly down to a temperature below 300° C. within 3 seconds, thereby forming a first layer of Ni-Sn alloy consisting only of stoichiometric NiSn phase brought about by both the reaction between said plated Ni and said plated Pb-Sn alloy and said cooling, a second layer of plated Pb-Sn alloy formed on said NiSn phase alloy, and optionally a Ni backing layer formed on said steel sheet, the total of both said Ni-Sn layer and said Ni backing layer, when present, being 0.035 to 1 micron in thickness.
Claim 2
Independent Claim
173 words
A method of producing a steel sheet plated with a Pb-Sn alloy, suitable for use as the material for automobile fuel tanks adapted to receive alcohol-containing fuel therein, said method comprising the steps of: (1) plating a steel sheet with Ni to a thickness of 0.01 to 1μ; (2) dipping said steel sheet in a plating bath of a Pb-Sn system alloy at 320° to 400° C. for 1 to 10 seconds to effect a hot dip plating; and then (3) cooling said steel sheet rapidly down to a temperature below 300° C. within 3 seconds, thereby forming a first layer of Ni-Sn alloy consisting only of stoichiometric NiSn phase brought about by both the reaction between said plated Ni and said plated Pb-Sn alloy and said cooling, a second layer of plated Pb-Sn alloy formed on said NiSn phase alloy, and optionally a Ni backing layer formed on said steel sheet, the total of both said Ni-Sn layer and said Ni backing layer, when present, being 0.035 to 1 micron in thickness.
Claim 3
Independent Claim
164 words
A method of producing a steel sheet plated with a Pb-Sn system alloy, suitable for use as the material for automobile fuel tanks adapted to receive alcohol-containing fuel therein, said method comprising the steps of: (1) plating a steel sheet with Ni to a thickness of 0.01 to 1μ; (2) effecting an electroplating to form a Sn plating layer of the Ni layer; (3) effecting an electroplating to form a Pb plating layer on said Sn plating layer; and (4) effecting a heating melting treatment at a temperature between 232° and 450° C., thereby forming a first layer of Ni-Sn alloy consisting only of stoichiometric NiSn phase brought about by the reaction between said plated Ni and said plated Sn, a second layer of Pb-Sn alloy formed on said NiSn phase alloy, and optionally a Ni backing layer formed on said steel sheet, the total of both said Ni-Sn layer and said Ni backing layer, when present, being 0.035 to 1 micron in thickness.
Claim 4
Independent Claim
164 words
A method of producing a steel sheet plated with a Pb-Sn system alloy, suitable for use as the material for automobile fuel tanks adapted to receive alcohol-containing fuel therein, said method comprising the steps of: (1) plating a steel sheet with Ni to a thickness of 0.01 to 1μ; (2) effecting an electroplating to form a Sn plating layer of the Ni layer; (3) effecting an electroplating to form a Pb plating layer on said Sn plating layer; and (4) effecting a heating melting treatment at a temperature between 232° and 450° C., thereby forming a first layer of Ni-Sn alloy consisting only of stoichiometric NiSn phase brought about by the reaction between said plated Ni and said plated Sn, a second layer of Pb-Sn alloy formed on said NiSn phase alloy, and optionally a Ni backing layer formed on said steel sheet, the total of both said Ni-Sn layer and said Ni backing layer, when present, being 0.035 to 1 micron in thickness.