The formation of the interface between electrolessly deposited Ni(P) and an alumina substrate is investigated. Prior to metallization, the substrate is cleaned, etched, and activated with Sn, Ag, and Pd-containing solutions. Changes in surface chemistry due to these pretreatments are analyzed with XRF and static-SIMS. TEM plan-view micrographs visualize the changes in surface structure during the pretreatments. The initial stages of metallization are measured on Si3N4 membrane model substrates. Cross-section TEM micrographs are made of a thin Ni(P) film on the alumina ceramic, showing a columnar Ni(P) structure, a thin interracial layer, and an intimate interfacial contact. Possible consequences for initiation and adhesion are discussed.

The interface microstructure and interface chemistry of dectrolessly deposited Ni(P) on alumina ceramics is studied in order to obtain insight into the influence of molecular interactions upon the adhesion. Detailed static secondary-ion-mass spectrometry, x-ray photoelectron spectroscopy, Auger electron spectroscopy, and transmission electron microscopy (TEM) analyses have been carried out with samples with various roughnesses, of which the mechanical analyses are described in the companion article. TEM cross-section micrographs showed a close contact between the two phases on a nanometer scale for all sample types. In addition, a 1-2-mn-thick interfacial layer was observed. This layer consists of nucleation material and compounds from the metallization solution. Fracture surface analyses showed that fracture takes place through this layer, which is therefore considered to be the weak,boundary layer in this system. The presence of this weak boundary layer explains the importance of substrate surface roughness and mechanical interlocking for the fracture energy.

When monosolvated alkoxide ions (R'O--H--OR*)-(R' < R2) react with boron, carbon, silicon, or titanium ethers, the major displacement reaction is always that where the smaller alkoxide (R'O-) reacts with the central atom, while the larger alcohol (R20H) becomes part of the solvated alkoxide product ion, e.g., (R'O--H--OR2)-+ Me3SiOR3 -(R20--H--OR3)-+ Me,SiOR'. Such reactions are exothermic and very fast: the slowest (silicon reactions) occur for one collision in everytwo. Such rates do not favor either (i) endothermic barriers or (ii) equilibria (ie., it seems unlikely that the specificity of reaction is due to thermodynamic control). The presence of initial orientation effects controlling the courses of reactions was suggested by ab initio studies (6-31G) for model systems (F--HOH)/H2BOMe and (MeO---HOH)/H,BOMe. In the former case, F hydrogen bonds to a methoxy hydrogen thus effecting subsequent attack of HO-at boron. Internal barriers are small. Ab initio calculations (6-31'G) show for equilibrium (EtO---HOMe) s (EtOH---OMe) that the mole ratio of (EtO---HOMe) is greater than 0.95. Thus in the reaction of (EtO---HOMe) with say Me3SiOR, it is proposed that initial approach of the two reactants results in the EtO-end of the nucleophile H bonding to R, thus directing subsequent attack of MeO-at silicon.

The thermal stability of a number of trialkylsilyl surface modifications has been studied. During heating, weight loss is recorded by thermogravimetry, while evolved gases are simultaneously analysed with mass spectrometry. Changes in the molecular structure on the surface are measured with solid state nuclear magnetic resonance (NMR) and static-SIMS. Degradation mechanisms are proposed and described by a number of reaction equations. The changes in surface chemistry on the internal powder surface as measured with NMR are similar to those observed with static-SIMS on the outer surface of the powder particles.