Despite popular belief that copper is a material that is always on the defensive and being substituted for, analysis shows the opposite to have been true over the last ten or fifteen years. In the late 1960's and early 1970's, copper was indeed the object of considerable substitution, particularly by aluminum in wire mill products. This aluminum penetration resulted in copper reaching its lowest market share at 71.9% of the total insulated wire and cable market in 1974, with particularly sharp aluminum inroads into power cable, building wire, and magnet wire (used to wind motors and transformers).
At about that time, safety problems, well publicized by the US Consumer Product Safety Commission, began to occur at connections in aluminum branch-circuit wiring used in well over a million homes up to that time. These problems were undoubtedly responsible for a sudden return to copper in building wire and some spillover effect into other wire and cable categories. Only in power cable, primarily overhead utility cable installed by highly trained professionals, has aluminum increased its market share since the mid-1970's. Today copper's share of the US insulated wire and cable market is about 78%.
Building wiring and plumbing have been the two top markets in recent years. Both have benefited from an increasing intensity of use (more electrical loads and more bathrooms in new homes). Plastics are an ongoing threat to copper in plumbing applications but their usage is still held back by their susceptibility to permeation by gasoline and other organics and to mechanical damage. They also do not exhibit copper's bacteriostatic properties.
Automotive applications, copper's third largest market, is the source of the most serious current substitution threat-aluminum in the radiator. Copper's answer to this threat is new soldering materials, better radiator designs, and new automated production techniques. Though aluminum has made inroads into the radiator, copper has gained far more due to the dramatic increase in wiring and electronics within the average car. Today, the use of copper and copper alloys in an average US-built passenger car is about 50 pounds, versus 36 pounds in 1980.
Telecommunications, on the other hand, has dropped from the number 2 spot to number 4 in less than a decade. Fiber optics is the popular explanation for this dip, but in fact it accounted for little of it prior to 1990. Other technological factors are responsible, such as subscriber carrier (piggybacking of many phone conversations on a single pair of copper wires) and the use of wires of smaller cross-section. This is a textbook example of copper applications being engineered for ever-increasing efficiency of use, which results in decreased poundage. Optical fibers are indeed a real threat for the future, however. Whether that threat is realized may depend more on cost factors than technical considerations.
Copper also goes head-to-head with aluminum in power utilities. Aluminum's light weight is its one advantage in current-carrying applications and it is used almost exclusively in overhead transmission and distribution cable. The advent of high temperature superconductors, today's hottest technical area, opens new vistas of possibility. Superconductors need to be surrounded by "shunt" materials, which can carry heavy currents around faults that occasionally occur in the superconductor. The mini-materials battle between copper and aluminum for the best such material for current-technology superconductors such as niobium-titanium has been won by copper. Superconductivity could be an important new market for copper, particularly in transmission lines, energy storage devices, and other applications not yet contemplated.
One negative of note for copper consumption is a large loss in copper's use in coinage. This occurred with a stroke of the pen in 1982, when a copper alloy was replaced by zinc in the penny. Roughly three-quarters of all US coins minted are pennies. A move is now afoot to create a new copper-base dollar coin, of more logical design than the ill-fated Susan B. Anthony coin, to eventually replace the dollar bill. Today's dollar is worth what a quarter was in the early 1960's, and Australia, Britain, Canada and many other countries have replaced their smallest denomination bills with coins.
A fact that is surprising to many is that when the markets are put on a usage-intensity basis-that is, pounds of copper used per unit of measure of each industry (use per housing start, per vehicle, per ton of air-conditioner capacity, etc.) -copper has shown increasing use in the last ten years. This is in contrast to the oft-quoted statement that the intensity of use of copper and other "mature" metals is falling rapidly.