Mechanical strength, lead alloys

Wrought lead—calcium—tin alloys contain more tin, have higher mechanical strength, exhibit greater stabiUty, and are more creep resistant than the cast alloys. RoUed lead—calcium—tin alloy strip is used to produce automotive battery grids in a continuous process (13). Table 5 Hsts the mechanical properties of roUed lead—calcium—tin alloys, compared with lead—copper and roUed lead—antimony (6 wt %) alloys. 

Lea.dAnodes. A principal use for lead—calcium—tin alloys is lead anodes for electrowinning. The lead—calcium anodes form a hard, adherent lead dioxide layer during use, resist corrosion, and gready reduce lead contamination of the cathode. Anodes produced from cast lead—calcium (0.03—0.09 wt %) alloys have a tendency to warp owing to low mechanical strength and casting defects. 

Cold-roUed alloys of lead with 0.06 wt % teUurium often attain ultimate tensile strengths of 25—30 MPa (3625—5350 psi). High mechanical strength, excellent creep resistance, and low levels of alloying elements have made lead—teUurium aUoys the primary material for nuclear shielding for smaU reactors such as those aboard submarines. The aUoy is self-supporting and does not generate secondary radiation. 

Let us note finally, that tellurium has been considered as an appropriate component for the lead grid alloy in lead-acid batteries, as improving its durability, mechanical strength, and anti-corrosive ability. In investigating Pb-Te binary alloys with different contents of Te (0.01-1.0 wt%) in sulfuric acid solution it was shown recently [104] that the introduction of Te can inhibit the growth of Pb02 and increase corrosion resistance of the positive grid alloy of a lead-acid battery. By the... 

The lead-free solders are mostly based on Sn-containing binary and ternary alloys. Among them, the Sn-Ag system is one of the earliest commercially available lead-free solders and has been recommended for general-purpose use as a substitute for Sn-Pb eutectic solder. Addition of nano-particles of second phase helps in improving thermo-mechanical properties such as melting temperature, mechanical strength, mechanical fatigue resistance, creep resistance and solder-joint reliability. 

Hardening mechanism in lead-calcium alloys. Lead-calcium alloys harden extremely rapidly 80% of the ultimate strength is reached in one day, and virtually full ageing in seven days. Such rapid hardening enhances grid handling and battery production. The rapid hardening was a benefit to VRLA batteries. 

Table 4.4 summarises the effects of As on the mechanical properties of low-antimony lead alloys [21]. Arsenic improves the hardness and less so the UTS of the alloys. If these data are compared with the required grid alloy characteristics presented in Table 4.1, it can be seen that lead alloys with addition of arsenic meet the requirements of the battery industry with regard to hardness and their tensile strength is close to the required values. 

One of the advantages of plasma spraying for producing HA coatings on metallic implants is that the substrate temperature can be kept relatively low. What possible mechanisms can lead to a loss in the mechanical strength of a metal if it is exposed to high temperatures (You can limit your discussion to the cases of Ti alloys and stainless steel.)... 

Lead in its pure state is very soft and has low mechanical strength. In this form it is used widely in the chemical industry, due to its high corrosion-resistance. Because of its low mechanical strength it is applied in the form of a lining to other, stronger materials. It is also used for radiation shielding. When alloyed with antimony, the strength and hardness is increased and it is used for the production of lead bricks for nuclear... 

---