US1633783A - Cutlery article - Google Patents

Description

f 1,633,783 D. J. GILES CUTLER! ARTICLE June 28 1927.

Filed March 25. 1925 WITNESSES INVENTOR I v 4 75 i 2 I 7 Patented .lune 28, 1927. I

UNITED] stares 1,633,783 E T Fries.

DAVID J. GILES, OF LATROBE PENNSYLVANIA, ASSIGNOR T LATROBE ELECTRIC STEEL COMPANY, OF LATROBE, PENNSYLVANIA, A CORPORATION OF PENNSYL- VANIA;

oU'rLnnY ARTICLE.-

Application filed March 25, 1925. iSerial No. 18,155.

The invention relates to articles of cutlery, such as table and carving knives, having steel blades provided with silver handles.

It is well known that the blades of such cutlery articles are of late frequently made of what is commonly known as stainless.

steel ,-a steel having a high chromium and relatively low carbon content, which, when hardened and polished, effectively resists corrosive actions such as are encountered in the customary uses of the blades oftable' and carving knives. For example, it has been amply demonstrated that stainless steel knife blades do not become tarnished when subjected to acid fruit juices, such as lemon, grapefruit, orange and likefruit juices.

'However, it has been foundthat stainless steel knife blades having silver'handles sometimes do tarnish or corrode, and, because the reason for this has been hitherto unknown, extensive investigations have been made by both steel and cutlery manufacturers to determine the cause of the corrosion so that it maybe eliminated. These investigations have included trials of various mixtures or analyses of steels, in which there were'va-. ried the relative proportions of the chromium and carbon content of the steels, and

in which various other alloying elements few drops were added, but all without success.

The object of this invention is to eliminate vthis objectionable tarnishing by the provision of a knife havlng a steel blade and a silver handle, the blade of which will not tarnish or become corroded whenthe knife is subjected not only to its ordinary uses, but also to its ordinary conditions of service.

The invention is illustrated in the accompanying drawings of which Fig. l is a side view of awknife, and Fig. 2 a side view of the blade and a longitudinal central sectional view of its handle.

The invention is predicated upon my discovery,1nade in an extensive investigation of the problem, that the occasional tarnishing or corrosion of the blades of knives havtion set up when the knives are subjected to such electrolytes as are not infrequently found in the use'and care of'the knives, as

action and resulting corrosion may be eli1ninated by separating the knife blade fromies were made.

mg silver handles is due to electrolytic ac-v its silver handle by a body of metal, of which portion is exposed exteriorly, and which is electro-positiveto both the blade and handl when the. knife is subjected toan electrolyte.

The invention may of the experiments in which these discover- To determine whether an electrolytic current is set up when a knife having a steel blade provided with a sterling silver handle is immersedin a solution of be fully understood by first making a briefexplanatlon of some salt water such as may be encountered in V the washing of table ware, I connected the handle and blade of such k ife with a very sensitive galvanometer and immersed it in a solution of 10% sodium chloride and 5% acetic acid. This experiment showed that an electric current of about one-twentieth of a millivolt was generated, and demon.

strated the necessity of further investigation to determine the nature of the electrolytic current and to arrive at a means for eliminating it, if possible.

To determine the nature of the electrolytic current I prepared a 10% solution of sodium chloride which was made just alkaline with sodium hydrate to insure its freedom from acids, and tothis solution there was" added of alcoholic solution of phenolphthalein. A reagent or indicator of solution, but is colorless in acid solutions.

thisvkind gives a'pinkcolorin an alkaline Hence, when a solution containing such an indicator is used as'an electrolyte, the solution appears colorless around the positive pole because of the acid there formed, and app-ears pink around the'negative pole. A knife having a steel blade and a silver handle was placed in a large test'tube of this solution, and within a short time a reaction was noticed, the solution around the handle becoming decidedly pink, which increased as the experiment continued, and the solution around the blade becoming colorless. V This experiment showed that the blade was'the positive pole of the knife, and hence sub- I jected to acid attack. As a continuation of this experiment, to determine the nature of the attack due to action of the-electrolytic current, the knife was permitted to stand in the solution for sixteen hours, after which it was found that the test tube: contained an insoluble deposit .017 5 grams of ironoxide, showing that the knife blade had been very definitely attacked by the acid formed in the solution due to the electrolytic cur rent or reaction set up.

Following this experiment a number of knife blades provided with handles of clifferent metals were similarly tested in electrolytes the same as that explained, to determine the direction of current flow through each. It was found that the direction of flow was reversed from that incident to asilver handled knife when knife blades provided with lead, aluminum, tin and zinc handles were tested, and that the oxides of the handles were deposited as insoluble so lutions in the electrolytes. In other words, the steel knife blades became negative poles in each instance, and the lead handle deposited lead oxide, the aluminum handle aluminum oxide, the tin handle tin oxide, and the zinc handle Zinc oxide. It was similarly determined that the direction of flow of an electrolytic current between silver on the one hand and lead, aluminum, tin and Zinc on the other hand are from the latter to the former, or in other Words in each instance silver is the negative pole of the cell.

A steel knife blade was then connected to a silver handle, the two metals being sepa rated from each other by a body of lead of which a portion was exposed exteriorly of the knife and the knife was placed in the electrolyte solution. In this test the solution around both the handle and the blade became pink, while the solution at the exteriorly exposed port-ion of the lead joint became colorless, thus showing that the lead joint was the positive pole and the silver handle and steel blade were negative poles of two electrolytic currents set up between the lead joint and the handle and blade.

, After the knife had been standing in the of metal having an exteriorly exposed por-- tion, and which body is electro-positive to both the steel blade and silver handle when the article is subjected to an electrolyte. The body of metal which so separates the blade from the handle may be any of the metals which have been tested and found satisfactory for the purpose, namely lead, aluminum, tin, or zinc, or may be any other tang 3 which extends into the handle, and

with a flange 4t adjacent to the heel of the blade. For separating the blade from the handle, tang 3 is preferably encased in a sleeve 5 of aluminum provided with a laterally extending flange 6 arranged between the silver handle and the blade flange 4, flange 6 being exposed exteriorly of the knife. As is customary in the manufacture of knives, the handle may be formed of a silver shell filled with a body 7 of rosin or lit-harge or both.

The presence of the aluminum sleeve, or a sleeve of metal having the characteristics explained, effectively prevents the knife blade from becoming a positive pole when the knife is immersed in electrolytic solutions such as salt water, or when wrapped in a rag which is moistened or saturated with an electrolyte such as may be encountered in the customary use or care of table ware.

I claim as my invention:

1. An article of cutlery comprising a steel blade and a silver handle separated from the blade by a body of metal having an exteriorly exposed portion and which body is electro-positive to both the steel blade and silver handle when the article is subjected to an electrolyte.

2. An article of cutlery comprising a blade formed of stainless steel, and a silver handle, the blade being separated from the handle by a body of metal having an exteriorly exposed portion and which body is electro-positive to both the stainless steel blade and the silver handle when the article is subjected to an electrolyte.

3. An article of cutlery comprising a'steel blade and a silver handle separated from the blade by a body of aluminum having an exteriorly exposed portion, the body of aluminum being electropositive to both the steel blade and silver handle when the article is subjected to an electrolyte.

at. An article of cutlery comprising a steel blade having a flange at its heel, a silver handle, said blade being provided with a tang extending into said handle, and a sleeve of aluminum separating the handle from the blade and provided with an exteriorly-exposed laterally extending flange, between the inner end of said handle and said flaiige of the blade.

In testimony whereof, I sign my name.

DAVID J. GILES.

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