3C Technology / "Process"
We proposed and developed a method for electroplating titanium alloys in the form of a coating
on plastic and carbon foams, and to develop reproducible and robust scaled up approach for
commercial applications. The reduction of titanium and zirconium before hydrogen will be
carried out in a diluted sulfuric acid solution, whose pH will be maintained at the value
of ~5 by using an appropriate buffer. At this pH value, the reduction potential of titanium
ions shifts toward more positive values. This effect has been demonstrated by the polarization
curves of the Ti–Zr system that was potentiodynamically measured in the sulphuric acid
solution . This behavior can be demonstrated using experimentally determined Pourbaix
diagram  that represents dependence of the reduction potential with change in pH
(a potential/pH diagram). The diagram shows the mapping of possible stable phases of an
aqueous electrochemical system in various pH conditions. In our case, when the pH of the
electrolyte is maintained at ~5, titanium is in the form of Ti02.
The initial steps involving surface activation and nickel plating were achieved without any complications. On the other hand, the process of titanium plating was difficult because the plating solution forms a very heavy suspension. We experimented not only with the composition of the initial solution but also with the additives to increase and stabilize the conductivity. In our first attempts we experimented with the composition of the plating bath, and we tried to plate several materials. During that development, the following elements were taken into account: 1) solubility of K2TiO3; 2) concentration of the final solvents obtained from initial highly concentrated (98%) sulfuric acids; 3) the pH of the plating solution (pH ~5) and a method of maintaining it; and 4) additives to the plating bath.
In our experimental set-up, the oxidation reaction occurs at the anode, which is made of platinum/titanium. Titanium ions Ti2+ move toward the cathode, where they are reduced and deposited as a metallic Ti. This process needs to occur before reduction of hydrogen ions. Our cathode is a nickel-plated over ABS/PC plastic or carbon foam element. Nickel acts as the cathode because it has been passivated and thus electrochemically inactive. In an electrolytic process, negative charges from a power supply are provided to the cathode where they reduce incoming ions. Passivated nickel cannot participate in near-electrode processes, thus only titanium or titanium/zirconium ions are reduced on the cathode, forming an amorphous layer.
Two methods of titanium deposition were designed and optimized. One was a conventional electroplating method—which used constant current—and another one was a nanocrystalline electrodeposition (we refer to as the “turbo method”), which uses pulse plating. In both methods electrodeposition of the titanium alloys proceeded from the sulfuric acid solution. Nanocrystalline electrodeposition (turbo) produces fine-grained coating with significantly improved mechanical and chemical properties compared to conventional constant current plating. Conventional plating produces larger sizes of grain deposits. The electrodeposited layer is a thick (>20000 nm); fine-grained coating (the average grain size is 6 nm–10,000 nm of metal alloy) of high resilience (>250 MPa), deposited at high rates (>2 μm/hr). Figure 3 demonstrates the difference between the two methods of metal electrodeposition. In the conventional method the size of the crystalline grains is in the order of 5,000-50,000 nm; therefore, our result remains in the nanotechnology field where the customary size of fine grains is in the range 10-10,000 nm.
3C Technology / "Plating On Plastics"
Crista Chemical Company LLC specializes also in plating a variety of di-electric materials including the engineering plastics such as ULTEMTM, Peek, PC/ACS, and Carbon Fiber with Electroless Nickel, nanoNickle and Electrolytic Copper.
3C quality philosophy is driven by a deep commitment to process control. It's one thing to develop a process that will produce good parts, but quite another to produce those parts day in and day out. Tight process control makes it happen! 3C works in accordance with all applicable ASTM, AMS, MIL, and Customer Specifications.