INDUSTRIAL AND ENGINEERING CHEMISTRY
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home building is now often painted on all six sides before it leaves the lumber mill. Aluminum paint is also extensively used on brick walls and steel factory buildings, to brighten and protect them. I n all of these uses one is reminded of the versatility of aluminum and the ability to manufacture it by various methods. It can be cast, rolled, formed, spun, drawn, ex-
VOL. 27, NO. 10
truded, and welded. It is therefore possible to adhere to a uniform artistic scheme, whether aluminum is used for buildings large or small, new or old. Aluminum is not only a metal for modern buildings, it is also used extensively in structures which rely on period architecture for their effectiveness. RECEIVED d p r i 1 2 7 , 1915
Nickel Alloys in the Architectural Field
T
H E nickel silver a r e well c l a s s i f i e d b y Nickel alloys are finding considerable use silvers (alloys designating the nickel content, in the architectural field, particularly for such as 8 per cent nickel silver, in w h i c h t h e hardware, plumbing fixtures, architec10 per cent nickel silver, 13 per p r i n c i p a l c o n s t i t u e n t s are tural trim, and roofing. A study has corcent nickel silver, 18 per cent copper, zinc, and nickel) have related the compositions of certain nickel nickel silver, 20 per cent nickel been developed, t h r o u g h imsilver, and 30 per cent nickel proved metallurgical t e c h n i c , alloys with their colors, and has estabsilver. from the ancient Chinese alloy lished a basis for intelligent color matchMO~VEL METAL. Except as Pnktong to the numerous coming with these alloys. The compositions it appears in U. S. Government p o s i t i o n s w h i c h are available and physical properties of important specifications a s “ a c o p p e r today. During the period 221 nickel alloys are discussed. nickel alloy,” t h i s p r o d u c t B. C. to 25 -4. D. many beautiful is known o n l y b y t h i s t r a d e “white copper,”or Paktong, ornaname. G. F. GEIGER AKD R . E. CASE ments were Droduced in China, but it was n i t until late in the The International Nickel Company Inc., STAINLESS STEEL. The type eighteenth century that the alloy of nickel-chromium-iron alloy New York, N. 1. used in the architectural field is was introduced in England and c o m m o n l y known as 18-8 or Germany. The attractiveness of KA2S. I n S a v y specifications it is referred to as corrosionthe product led to efforts to identify and duplicate the alresisting steel. This alloy is also covered by a large number of loy, Some fifty years later we find the almost simultaneous trade names. Of the many different types of stainless steel on appearance of Merry’s Metal Blanc (in England) and Argentan the market this 18 per cent chromium-8 per cent nickel, or German silver (in Germany). These and variations of with 0.08 to 0.20 per cent carbon, is of especial interest to the original composition are known today as nickel silvers. the architect. This type of stainless steel has a diversified Twenty-nine years ago the ores of the Creighton Mine were applicationin building construction. It is particularly adapted found to contain about twice as much nickel as copper. Colofor out-of-door metal trim, since it is highly resistant to atnel ,Vonell conceived the plan of producing a natural alloy by mospheric corrosion. refining the copper and nickel together, eliminating the separation process heretofore employed. The experiments met with successful results and the product developed was called Color and Color Matches “monel metal.” -4third group of nickel-alloyed white metals is the stainless The demand for alloys in the white range that can be used by architects in developing mild color contrasts or matches steel group, The element chromium was isolated in 1789. has led to a study (1) of the relation between color and comThe corrosion-resisting properties of the chromium-iron alloys position of a series of copper-nickel-zinc alloys in which the were appreciated in the early part of the nineteenth century nickel content ranged from 1.5 to 25 per cent and the zinc (about 1821), but not until about twenty years ago were there from 0 to 50 per cent. The effects of tin up to 8 per cent any appreciable commercial developments. Since that time and lead up to 10 per cent were also studied on certain zinc many steel manufacturers have entered the stainless field, levels. making claims for their particular analysis. These, however, are now clearly and well-defined products, with application I n order to cover this range of alloys, it was necessary to compare alloys produced by the and l i m i t a t i o n well e s t a b 30 three commercial m e t h o d slished. extruded, rolled, and cast. Figu r e 1 s h o w s the approximate Terminology ranges of nickel and zinc in the SICKEL SILVERS. This group LO cold-working, hot-working, and casting alloys. i s c o m m o n l y called “white I n the cold-working alloys the metal..” I n the metal market nickel may range from 10 to 30 these are sold in the cast and /O per cent and the zinc from 5 to r o l l e d f o r m s under the trade 30 per cent, depending upon the n a m e s of R e n e d i c t M e t a l , R desired physical p r o p e r t i e s , Ambrac A, Ambrac R, White color, and tarnish resistance. B r o n z e , a n d Nickel Bronze. 0 0 /O 20 30 40 64 There are two hot-working or The latter two are chiefly used by the hardware men. zi - h C e x t r u d i n g ranges: (1) nickel The various grades of nickel FIGURE1. COMPOSITIOZ~ RANGESOF NICKELSILVERS from 12 to 28 per:cent:and zinc
‘ .t”
$
OCTOBER, 1935
IXDUSTRIAL AND ENGINEERING CHE-MISTRY
from 2 to 6 per cent and (2) nickel from 8 to 18 per cent and zinc from 38 to 45 per cent. Here again the alloy content depends upon the color and properties desired. I n the casting alloys, where it is also necessary to consider machinability, melting point, and fluidity, the nickel range is from 12 to 30 per cent, zinc 5 to 15 per cent, lead 2 to 10 per cent, with tin up to about 6 per cent. Sickel exerts a powerful decolorizing or whitening effect in the copper-nickel-zinc series. In the presence of sufficient nickel, zinc also has a mild whitening influence. Tin and lead do not give marked color changes in the amounts generally present in commercial nickel silvers; however, they have a slight effect, which varies with the nickel and zinc contents. Figure 2 shows the gradual color changes which accompany changes in composition within the limits stated. Alloys which are considered “white” are indicated by the shaded area. Increasing the nickel content produces a very marked increase in whiteness away from the yellow cast, except in the highzinc (40 to 50 per cent) range, which, with 20 per cent nickel, has a blue-white color resembling chromium plate. The drawn 20 per cent nickel silver, which contains about 5 per cent zinc (Federal Specification WW-P-54I1) is widely used
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contain 38 to 45 per cent zinc, good corrosion resistance is maintained with 15 per cent nickel. Experiments were conducted by Vernon ( 3 ) to determine the effect of a “kitchen” and “basement” atmosphere on nickel plate, pure nickel, and several copper nickels and nickel silvers.
Per Cenf Mcke/
FIGURE 3. COVPOSITIOY LIMITSOF CASTING ALLOYSTO MATCH20 PER CENT NICKELSILVER PIPE Alloys contain 2 per cent tin and 4 per cent lead.
In the kitchen tests the alloys became “fogged” with a creamy white film. The higher the nickel content the sooner the fogging started. After the specimens were carefully washed with alcohol, the relative appearance of the specimens was reversed. The pure nickel was restored to its original brightness, while the nickel silver was somewhat tarnished. I n the basement tests where the humidity was lower, there was no sign of fogging; however, there was evidence of tarnish which was most pronounced on the copper nickels, only slight on the monel metal, and not visible on the nickel. Table I shows how the compositions of commercial nickel silvers must be different, depending upon whether they are rolled, extruded, or cast, if a color match between the three classes is to be insured. I
f A5
I
20
I
2 . 5 -
JO
Z FIGURE 2.
N;cke/ COLOR TREIVIIS OF SIMPLECOPPER-NICKELZINC ALLOYS
The shaded area indicates sensibly “white” alloys.
for piping in conjunction with cast plumbing fixtures, and fur this reason a study was conducted to determine the range of cast alloys which would give a good color match. I n this study the nickel and zinc were varied, while the tin and lead were held at approximately 2 and 4 per cent, respectively. Figure 3 shows the composition limits which give a good color match in freshly polished metal. It will be noted that the sum of the nickel and zinc percentages equals about twentythree. Tarnish due to atmospheric exposure will change the color relationship of these alloys, especially when the nickel content differs to some extent. However, the cleaning which is required from time to time to remove dirt is generally sufficient to retain the original color. Tarnish resistance is chiefly controlled by the percentage of nickel, although zinc is helpful. I n casting alloys where the zinc is relatively low (around 6 per cent) the nickel content should be a t least 20 per cent. I n the extrusion alloys which 1 This and other U. S. Federal Specifications referred to in this paper may be obtained from the Superintendent of Documents, U. S. Government I’rinting O 5 c e .
T.4BLE
I. COMPOSITIONS
Name
OF
COMMERCIAL NICKEL SILVERS
10% nickel silver
Extruded Per cent cu 49.5 Zn 40 0 Ni 10.0 Pb 0.5
13% nickel silyer
cu 811
Xi Pb Fe Impurities
ZO’% nickel silver
...
40.5 44.75 13.0 0.75 0.25 0.75
Drawn, Rolled, Tubing Per cent Cu 65 Zn 2 4 . 5 Ni 1 0 . 5
Cast Per cent c u 55 Z n 20 Ni 1 2 . 5 Pb 1 0 . 5 Sn 2
Cu 5 5 . 5 Zn 2 9 . 5 Ni 1 5 . 0
Cu 55
c u 75 Ni 20 Zn 5
C u 65.25 Ni 20.0 Sn 3 . 0 Pb 6 . 0 Zn 7.5
Zn Ni
18
15
Pb 8 SI1 4 Mn 0 . 1 6
Mn 0 . 2 5
Specifications, Compositions, and AI ailable Forms SICKEL SILVERS. There are no government specifications for the 10 and 13 per cent nickel silvers covering these niaterials for architectural purposes. U. S.Guvernnient Federal Specification WVW-P-541 covers the 20 per cent nickel silver for plumbing fixtures (for shore purposes) in its four available forms: (1) cast, ( 2 ) drawn, (3) leaded, and (4) wrought. forged, or pressure die-cast.
